My vmax rx7 build

Author
Discussion

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
OK, well ive decided to start my project thread, been meaning to do this for a few weeks but never got around to it, im hoping for as much advise as you guys can give me and hopefully this will be alot of fun.

Right lets start at the beginning, after looking around for ages to get myself my next car i get myself a budget of 3-4k for something.

My criteria was that it would have to able to take a good thrashing and i didnt have to watch the rear view mirror for smoke everytime i put my foot down(5yrs of running a 12sec r5 turbo)


so i was left with an evo 4, and rx7, 200sx and a r32 gtr.

After thinking, well how fast do i want to go and at what point with would i be happy i had enough power i sat down and thought, well my 5 was 325bhp/ton and i want to go faster than that so im looking at 450bhp evo/200sx, that will cost a fortune and will only match my old car.

I then did some more research on the gtr, at 4k im looking at the very bottom end of the market and id again need 470-480bhp to match it, skyline tax is pretty bad and id need at least injectors, turbos etc to get that.

So finally i looked around and after watching many a youtube video and also alot of initial d i realised the best handling and cheapest car for big power was the rx7.

So basically lived on beans and noodles to try and set myself a decent timescale to get the money together, i then started to look at cars.

Eventually i found one in derby, pics look good and was decently priced at 3k
(pic below)


when going to see the car i marvelled of how good condition it was, not a spot of rot, with it coming into the uk in 2006 and only done 55k it was worth it, i knew the clutch was on its way out, but compared to 6k for some of the others id seen i thought it was a bargain.

Well a few weeks later it developed a water leak, because of the undertray and the cramped engine bay i couldnt work it out where it was coming from, since it only did it after driving for about 10mins i took the guess that it was coming from the overflow on the AST, so i blocked the overflow and took it for a very steady drive for 5mins, looked underneath and no water, thinking i had cracked it, i headed home and pulled outside only to be greeted with an bang under the bonnet

(im sure you can guess what happened)

The plastic AST exploded! So im stuck with a problem, OK, ill just bridge the between the 2 hoses using a hollowed out pen as it seems to fit the bill and people on the forums say they run without an AST anyway.

So drove it around for a few days, everything seemed fine, even had a couple of 160mph top speed runs...seems people on the forums were correctsmile

Anyway came to my car one morning only to see it surrounded by water, popped the bonnet to see my main waterpipe to the top of the radiator has exploded during the night, ribbed it literally in 2 and i find its my main water hose that was leaking that caused the leak but because the water ran to almost the other side of the engine bay before dripping onto the floor it made it hard to work out it was from there.

A call to WGT to see if he can get one for me, he says he will get one ordered, we after waiting a few days and getting panicky as its my daily driver for work i ring him again to see whats happening, after some research mazda have told him that part is not currently being made anymore, the company mazda used to have make them has gone bump so thats it.

A search of ebay i find a guy selling them blue silicone ones for £29.99 for the set and he only lives 10mins from my house, beats £50 for rubber ones from mazda!

After fitting them i dashed up to WGT to get a metal AST to save the same issue happening again.

Well after a few months i decided i wanted more power so installed a set of second hand HKS filter kit i got cheap(£70) from carl at harward.

Then a month later i fitted a xspower cooler(£120) with the idea that id build some ducting in the future after fdash's decent results with his so the engine bay looks like this.


A few weeks after i decided the clutch really needed to be sorted, i could drive the car but as soon as i put my foot down it would slip madly.

Talking to pip again we discussed clutches and i went for a stage one uprated exedy clutch thats rated for 340ft/lb which i thought should be enough to keep me going for a while.

While i was in for a clutch i got the chance to watch and film this monster being mapped


Well from this point i was pretty happy with the car, drove really well and was alot of fun, though there was no camber at the front and would understeer at the limit so i decided suspension would be my next port of call.

After asking a fduk member about his suspension he offered me his set, only been used in the dry and hardly done any miles, pretty much like new for £300


so after fitting them and messing with the dampering and ride height i noticed alot more grip on the front end by gaining camber, first test was the local roundabout that i used to understeer around, well a big second gear sideways moment definetly told me the front end gripped better!

Looks alot better aswell



So this brings me up to the more present time.

NOW THIS IS WHERE IT GETS INTERESTING


My water seals had been going for quite along time, so i just kept topping the water up but it finally got to the point of no return so i was left with a non-running rex, luckily i knew this would happen eventually so i had been saving for quite a long time in the event id need to get my wallet out.

Now im sure you have been browsing ebay and seen the advert for the rx7 rebuild guy, well i decided to give him a ring and see what he had to say.

Now what can i say about this guy, most companies ive ever called in the past cant get you off the phone quick enough but steve rivett was completely the opposite, if you call him you best have a good 1hr of your life free to talk.

We spoke about everything rotary from the simple stuff to everything complex, never have i met a guy so passionate about what he does, or infact so honest. He told me about the first 2 engines he built that didnt even last 500miles because of mistakes he made while he was learning, that spoke to me about how open he was, i would never imagine any other tuner tell you about there fkups! He is a retired engineer and only started this because his son is a racecar driver and owns a rx7 trackcar.

So after a long chat i decided to take my car down there, upon arriving im surrounded by other rx7s that hes working on, he borrows a garage from a friend in return for looking after his rx7(also owns a f355 and f40!), this was all very grass routes stuff and i like the personal touch he gives.

Anyway, we begin talking about what he will be doing to the car and what i want from the car.

This is the point where we sit down and have a good think, realistically how much power do i truely want, what level will i need to be at that ill never want anymore, i come to the conclusion that 500bhp should be enough.

So he shows me this tools and we talk about porting, he owns a set of racing beat large street port templates and shows me a current engine he is in the middle of porting. We look at rjpartri dyno graph to see what he has done in the past.

this is on twins with 0.8bar of boost, as you can see its making good power up at 8k, if was even making decent power at 8.5k and from what ive read that means that the ports are quite large and are flowing well.

So since he has never built an engine that he knows is going for 500bhp we talk some more about the porting, using the templates to start him off, once he has done that he is going to push the porting a bit more than normal for maximum flow, also hes going to port my UIM, LIM and remove the secondary throttle.

Finally when building it back up he will fit a sump brace and fast reacting air temp sensor to help out in future mapping.

This now brings me onto bolt-ons to make the power.

TURBO kit

Im going for the rx7 store GT4088 TURBO KIT


Which according to the compressor maps should flow a nice 550bhp at 1.3bar


ill need a 3inch decat which i can get done cheap locally
a power fc to control everything

FUEL

Im going for the rx7 store Extreme Fuel System

with uprated fuel pump of course.

Now intercooler is where im unsure of, ive looked at the ebay greddy style setups but i need to do some more research on them to see what sort over power people have made on them


All in all including my rebuild im budgeting 5k to acheive this, which aslong as im careful with my money i believe is achievable.

This very much is a budget build so im not gonna be throwing 3k t51r kits around.

So what does everyone think, the car will be ready to run the engine in 2weeks time, so it will be a while before its on the dyno but im pretty hopeful.

I will update this thread as i go along but everyone is welcome to comment good or bad as im happy to learn off anyonebiggrinbiggrinbiggrin

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
after chatting to a mate i went back to my engine builder to talk more about his porting, he spent all weekend researching to see how much further he could go, then spent monday increasing the size of the ports again, should be interesting as they are now exactly the same as these pics below and the info on what it should run like.

stock vs big port


overlapped each other to see the difference.

the info on this says:

Same as port style 1, but with advanced port timing. Gives awesome power through the midrange and spools turbos a lot quicker. This is the port where your idle quality deteriorates. A reasonable idle of 800-900 rpm can still be achieved, but you’ll notice some misfiring due to the extra port overlap. Vacuum signal typically between 14 and 16” @ 900 rpm. This port can be customized to your specification. Gas mileage either stays about the same or decreases slightly, but 20+ mpg on a properly tuned setup is still attainable, depending on weight, driving habits, etc…. stock turbo(s) is inadequate and should be upgraded. you’ll see the best results with an engine management system.

also decided on my intercooler setup so now its just a case of waiting to get the money together to bolt stuff on

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
got some pics from steve

engine out and bay looking a bit dirty!!


removed secondary butterflies


inlet manifolds



throttlebodybiggrin

engine plate porting







Housing ex porting

nice housing surfacesmile


engine ready to buildcool


Engine block builtbiggrin


bolt ons added for running engine in




shall be fetching the car on wednesday, cant wait, then its the 1000miles of walking pace!

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
picked up the car wednesday

where the magic happens!


a car steve is working on at the moment, having fun with electrics


my baby!


all in and ready to go


well got the train down there, spent ages chatting the usual rotary stuff, coming up with ideas and generally trying to stay warm, my god it was cold!!

any we come to start it and it wont start, spent ages trying to work out what it was and finally found that one of my brand new NGKs had died even though it was running fine the day before.

After replacing that and getting it started what can i say....my god the noise, not quite the brap brap of a bridge but its lumpy as hell, reminds me of when you put a set of extreme cams in a piston engine. just shows how much extra air is going into the engine!

so pretty much just pootling around at the moment until i have the money for a power fc but it desperately needs it as it hunts like mad.

So thats pretty much it, all will be quiet for a while now while i save my money, so next is power fc, then intercooler/rad setup, injectors and map but its nice to do 450miles and the coolant hasnt even moved lol

sorted out intercooler and rad setup

600x410x70mm core! should be ample coolingbiggrin



radiator.....looks twice as thick as the standard crappy one when i saw one down steves


got a seat from a friend today



stripped it down and repainted the back in mazda classic red i had spare


just need to order some bases to bolt to the floor now, think im gonna get them from a guy called atomicrex

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
Baffled Spoon said:
Car looks great - few things look as nice as an un-chavified rx7. Very comprehensive build too. I've been having a disturbing urge lately to get an fd rx with a blown engine and swap a ls2 v8 into it driving
that seems to be the popular thing at the moment, a rebuilt rx7 is worth 5-6k, blown engine or water seal failure(like head gasket) is only worth about 1k so most people break them for parts.

I did think about the V8 conversion but decided ill stay with the rotary as i love turbos and i love revs so this suits me well, im up to 600miles now so the engine is nicely bedding in, though staying below 4k sucks, should have my ecu just after xmas if i avoid buying everyone xmas presents!

Just to let everyone know the reason i called this my vmax build is because the UK record for the fastest rx7 stands at 183mph which to be fair isnt all that impressive, my plan is to beat that record late next year at a vmax show, infact im looking at turbos again because id like to be the first rx7 to break 200mph in europe which my calcs say ill do it with 630-650bhp at brunters

Edited by turbotoaster on Sunday 13th December 01:20

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
well im not to fussed about all the drifting thing ill be honest, it would be nice to have a go at a training day just purely so i can learn the car a little better, but that would be mainly so im a much better grip driver. the car was designed to be one of the best handling cars to come out of japan, so thats what its gonna be used for, use its strengths, if i wanted to go drifting id have bought a 200sx

the bodywork is a big debate in my head to be honest, im not bothered about big gay wings or anything like that, but depending on temps i might need to change my bumper, but then its the offset of extra air going into my engine bay(larger opening) verses more drag hence ill buy one if really required but id rather spend money where its needed than purely looks.



here is my engine bay design, it took a fair bit of working out, it may look simple but noone has a setup like it in the uk, most go for v-mount kits or put the intercooler in the bumper and leave a gap between the rad and cooler, my design was partly inspired by how the cossie guys do it and also by a bit of common sense, for example v-mounts work, but if your blasting that got air upwards through the cooler and it hits the bonnet, where does it go from there unless you have a vented bonnet and thats something i dont want for the moment, also v mount kits for an rx7 cost around £1k and im not prepared to that.

Ok ill explain the colours above to give you an idea

red is radiator
green is rad fans
blue is the intercooler
grey is aluminum ducting

theses sizes are from what i have researched on the cooler rad im using but they are just a guide hence the quick draw in paint.

now the reason this should in theory work in my setup is the ducting, the intercooler will be fully ducted at the top, bottom and sides, this air will be drawn through the front bumper and the ducting will connect directly to the bumper so that any air entering will have to travel through the cooler, also because there is no gap between the rad and intercooler it will be forced to travel through that aswell.

The only thing that might need adjustment is heatsoak from the rad to the cooler when they are touching, if that is the case, ill move the cooler 1cm off the rad and close the gaps again with ali, but its worked on alot of racecars so we shall see. A bit of research into air flow diagrams and also my alevel physics means that although the bumper opening is smaller that the full area of the intercooler it will still work effectively because the area between the bumper and the cooler expands the air starts to slow down, but if im doing say 100mph if the air is only hitting the cooler at 70mph then it wont make any difference as in theory it will travel through the cooler slower in turn taking more heat away.

Sorry if im waffling on but i love talking about stuff like this.

turbotoaster

Original Poster:

655 posts

174 months

Sunday 13th December 2009
quotequote all
tommy18 said:
good work mate! i have a single turbo fd too! great cars! was the rebuild cheap compared to some of the big name tuners?
well a basic rebuild is 1850, no vat or anything like that, theres basically 1050 worth of parts and he charges 800 to take the engine out, strip it, rebuild it, put it back in and give 12month/12k mile warrantee, for that money i thought its not worth doing myself. My build was a fair bit more than that as i had alot more stuff done, ie i had new rotor housings instead of reusing my old ones as i wanted perfect compression and alot of little changes and porting along the way.

turbotoaster

Original Poster:

655 posts

174 months

Monday 14th December 2009
quotequote all
Gaz. said:
What are you going to do with the air when it leaves the radiator?
to be fair im not 100% sure, i know there is potential that ill need to do something but racing beat's rx7 is the world record holder at 242mph down bonnieville and thats not exactly the coldest of places, ive emailed them as they ran an unvented bonnet to see if they had any problems with temps

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 15th December 2009
quotequote all
hotshot123 said:
so did you managed to keep it under budget? how does it run in ported freshly rebuilt form?

very interesting read btw!
at the moment work has slowed down because ive ran out of funds, i didnt have all the money in a bank account ready to go, so ill justy slowly be adding bits as funds come in, first thing is an ecu, then we can start with cooling.

the engine is all built and im running it in at the moment, its done 600miles up to yet, its a little lumpy and the overlap on the ports does cause a bit of misfiring if you holding the car under 2000rpm, but to make the power i want im not gonna expect perfect streetability.

Got an email back from racing beat:

Your question was forwarded to Jim Mederer, Racing Beat's co-founder and chief engineer, for review. The following is his reply to your inquiry:


Our Bonneville FD had a custom chassis with no part of the stock chassis. I made the driveline tunnel quite large to allow heated air to pass through. The entire car had a carbon fiber underpan bonded to the chassis. I used a 4" thick radiator to restrict air volume while maintaining high speed cooling. Intercooling was done with ice and water to reduce drag. I urge you to use a 4" to 5" high spoiler lip to obtain down force at the rear - critical for traction and stability.

Jim Mederer


Now he was flat out for 4miles straight so im not gonna be generating quite as much heat as he is, but its an interesting way of getting rid of heat, from what he wrote im guessing he was using a chargecooler setup, i have thought about that myself as ive got a bookmark for a company in US that will sell me a kit rated for 1200bhp for 469 dollars, im holding off on the intercooler at the moment even though ive designed my setup the best way i know until i look into it a bit more.

The aim of the car is to do it once and once only, im not going to be upgrading things i have already messed with as its a waste of time and money.

Ill admit the 5k isnt going to be achievable as i need to spend about about 3k and ive already spent 3k but the car cost 3k so if i can complete the car including buying it for 10k(1k to cover for extra bits and bobs, like w/i) i think ill have achieved something special.

Cant think of any 200mph 600bhp cars you can buy for 10k, apart from maybe an old v8 drag car!

Edited by turbotoaster on Tuesday 15th December 20:18

turbotoaster

Original Poster:

655 posts

174 months

Wednesday 16th December 2009
quotequote all
right bit of an update.

Spoke to reworx down south and they are happy to map the car, come with me to brunters and be a passanger with the laptop and help with my 4" exhaust.

Also spoke to STAV and he is gonna do a feature in redline when i go to brunters so it will be nice to share it with the rest of the country.

Also the budget for the car including actual buying it for 3k is 10k, im going to prove you dont need silly money to hit 200mph, its all in the parts and thinking outside the box, as you can imagine STAV loves the sound of that hence why ill get a feature

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
Been thinking about this for the last couple of months and ive decided to go for it!!

On another forum there was a debate about how much it would cost to do 200mph within 1.7miles(airfield)

The thread went a big barmy when everyone had all the little groups throwing there dummy out and a few extras pitching in for the fun, at the time i didnt really pay that much attention to it, just sort of skimmed to top of it.

Anyway while reading the one thing i picked up on was a magazine reporter from Redline, mr stav/steve. He claimed that you could go 200mph for £10k, of course everyone claimed that was rubbish but he stuck by his guns and made a few examples that made sense to me.

Yes you could build a multipurpose car that will happen to do 200mph with all the shiny alloy bits on and spend a fortune, but if you had one goal in mind and nothing else i believed it was possible.

Now i wont really turn this into a build thread as such as it will be probably be moved and id like to keep it here for everyone to see as i think this section brings in the most experience and knowledge

So a quick run down, the plan is to buy a car, tune it and make it run 200mph at brunters for £10k.

Already spent a long time chatting to guys who have done it before about this and hes give me lots of useful information and seems to back me up on this.

Spoke to Stav and hes gonna do a full magazine coverage and pay for the day etc so its a definite goer!

ill put my ideals below


The reason this car will work is that alot of the things i require are already with the car.

It has a very low drag coefficient body 0.28 which means cutting through the air is easier, it has double wishbone suspension all around which adjustable camber from factory.

I have fitted a set of tein coilovers with alloy top mounts, i got these from a friend who had only done 1000 dry miles on them for £300, this gives me the ability to make the car very low to help with aero, ie fast under, slow over creating downforce.

Now up until last year there has never been forged components for the rotary engine, its just something thats never been developed because of the complexity and the tooling cost.

This means that every power rotary engine has always used stock internals. Those 1300bhp rx7s you see at the drag strip are running the same bits that the guy up the street is running on his stock 250bhp rx7.

Now the benefit of this is the lack of parts that needs to be bought, when your going for big power on a piston engine most people 'forge' the bottom end by spending say £1k-£3k on rods, pistons and maybe a stroker crank.

Another benefit of this engine is the lack of cams, valves.

Now if you want more power from a piston engine you normally need more aggressive cams so you can get the air in and out alot easier, which can cost alot of money, some people pay up to £4k for a worked over head with lairy cams.

To do the same on a rotary all we need to do is port out the housings, now this costs anything from £200 put to £500 depending on where you go and what you have done.

For my engine, we have gone for a large port and also ported the inlet manifold, removed the extra throttle butterflies to help with flow.

This is the same as flowing the head and putting in more aggresive cams, gives the ability to make power higher in the rpms and also due to the extra flow of the port also means that the turbo will spool earlier.

Ill post this now and type the next bit up

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
now when speaking to Rod(done 206mph) he mentioned to me that i would need roughly 630-650bhp to achieve 200mph, now thats in an ideal situation, ie im making that power at exactly 200mph, this brought me on to how much power do i actually need, the first thing to do is have a look around at a few compressor maps and also a few examples from the US/OZ

Now the problem with rotarys is they are very un-efficient with the airflow that they recieve, for every 10lb of air they receive they only make use of a max of 7.5lb of it.

So to make say 750bhp ill need a 1000bhp turbo if everyone follows me?

because of this un-efficent process the forces are not used fully for movement and are passed onto heat, hence why rotarys run so hot and also produce really high EGTs in turn because of the high EGTs the energy is passed out of the engine and into spooling a turbo, hence you can run a very large turbo for its engine capacity.

I did look at the garratt range of turbos but since this is very limited in budget i decided to discount them.

This left with me with a few other brands, mostly american diesel turbos. Now a company a few people may have heard off called Borg Warner are becoming increasingly popular in the performance market

Ill type up the next bit on my turbo choice in a second

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
ok there are many different turbos from borg warner.

I have decided to go with a s475 which can flow 100lb/min with a 1.15 A/R rear end, i can go larger on the rear but decided this is a good compromise between spool and top end power.

I can give full specs of wheel sizes if anyone needs it

to give you an idea of size, here it is next to a coke can


It will normally outspool the equivalant GT4202 by 400rpm on a rotary and they ony cost £400-£600 from USA so a bit of a bargain!

Obviously you have this massive turbo, your gonna need to connect it to the engine, this is where a forum member on pf called rickylee comes into force.

Now after seeing his manifold he made on his turbo civic build thread, after seeing that i got in touch with him about making me a manifold, really nice chap and he will be building it, will also run a 5inch downpipe to help with spool and top end power which will exit behind the drivers side wheel.

Ill be using a 60mm wastegate and the manifold will be a t6 divided version to help out boost threshold

looks like this


turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
now your throwing an awful lot of hot air around into an engine that is known to run hot anyway.

Without proper thinking its a recipy for disaster.

The standard radiator is around 30mm thick and does a decent job for a standard car but very quickly reaches its limit once your running alot of power.

Alot of people choose to keep the stock one for a while when running single turbo, the reason for this is 2 fold.

1. because most single turbos are only oil cooled you have one less hot think to dump heat back into the water system.

2. because of the larger rear end of a single compared to the twins theres less restriction for the heat leaving the engine, this in turn helps get the heat out of the rotary engine faster, this was something i read and im sure theres a better way of typing it, but ill leave that for improvement.

Now im not just gonna run 400bhp on this engine, im looking nearly double that, so its silly to believe that the stock rad can cope.

Luckily the ebay rads you see for sale are only £120 and are proven to work on big power cars, they are 58mm thick which is a big improvement and are cheap as a bonus.
so got this one

The car runs 2 oil coolers as stock and they are pretty good at controlling oil temps even on heavily tuned rx7s.

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
well ill be going with a power fc, its easy to tune and pretty versatile
It arrived in the post from japan.


yes something like a autronic/motec would be better but theres some big numbers being done over in the states on this ecu and money is an issue.

The good thing about it is the commander which can monitor everything the ecu sees, saves me buying a few gauges, for example at can see all the below in real time

Engine RPM
Ignition Timing
Vehicle Speed
Air Flow Voltage (Pressure Sensor Voltage)
Injector Duty Cycle
Boost
Knocking Level
Battery Voltage
Intake Air Temp
Water Temp

Thinking about injectors i did some calculations and for 700bhp a rotary needs 5500cc/min of fuel(not 100% duty, about 85%)

now ross at dragon performace and the guys at reworx both suggested i go with 6 injectors instead of trying to fit massive injectors into the primarys and secondarys as its alot harder to map.

so we talked about maybe 6 x1000cc injectors, but then that comes down to budget again.

I was watching a guy in america running 9s quarters running a stock ecu with a peter farell piggy back ecu controlling extra injectors, he was pushing 600whp+ which is the numbers im after.

i sat and thought about it a couple a nights ago and thought how can i do it.

it then came to me, i already have 2800cc of the injectors in the car at the moment, i only need another 2700cc and im sorted, both tuners recommended 6 injectors, so why dont i put 2 x 1600cc injectors in, that 3200cc worth of fuel, more than enough, watched a few videos of some monster rx3 and he was running extra injectors in his Upper Inlet Manifold and ive decided thats where they are gonna go, on the secondary port sides(outer edges) this means i keep my stock primarys for driving around like miss daisy, also keeps my afr while idling as normal and normal driving ill be ok

Fuel pumps will be 2x 305ltr pumps running in tank which will give me more than enough fueling

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
one thing i havent mentioned here aswell is that the car will be running pre-turbo water injection, im making my own kit aswell and it will be a purely mechanical system so no pumps involved, got this idea from a couple of guys in america doing it, one guy runs 23psi on pump fuel on a big turbo daily, the other runs 32psi on pump fuel and has 700bhp.

this design isnt mine but im using it to give you an idea how it works.


very simple set up, good thing is, the solenoid will open at say 1bar(depends what i set it at) and the more boost you are running, the more water, so theres no need to fiddle with jet sizes once you have set it up to flow the right amount of water

Ill be running around 2bar of boost pressure

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
ok onto the deal with power, i did some gear testing yesterday to determine what needs to be done

So i went out with my gps meter to do some gear testing.

to do 100mph(gps) i need to do 4500rpm, give or take 20rpm

so to do 200mph i need to pull 9000rpm, simple maths. this is on 255/40/17s there maybe 1mph more for tyre expansion but ill leave that out to make it easier. also a 4.1 diff

So i got out my gear calculator program i have to put the numbers in to see how i can help.

online i have found that the 5th gear results are much longer than they should be, 0.719, which must be incorrect else id be doing a massive speed.

Anyway i adjusted my 5th gear till i got 100mph at 4500rpm with tyres stated earlier.

This gave me a 5 gear ratio of 0.820 or 22.15mph per 1000rpm.

Now according to what the guy with the stock port and same turbo as me did, his max power was at 8200rpm, because of my big streetport im calculating that my max power will probably be about 8500rpm.

So to do 200mph im going to be past my max power and its gonna be trailing off, not good really at that means ill have less power where i need it most.

At my maximum power ill only be doing 188mph, so well short of the mark, so lets change the diff to an auto one to see what we can do.

now this changes the speed at max power to 198mph, which is much better, very close to the mark.

Ill have to wait to see what my final max power/rpm will be but it least im making progress on gearing.

also say for example i only make max power at 8200rpm like the other guy did i can still hit 200mph with 8250mph if i change my rear tyres to 255/45/17

hope this clears up any potential confusion people have had in the past


One thing about power is if i made 1000bhp at 6k but only 500bhp at 9k and i need 9k to hit 200mph i wouldnt do it.

But if im making 1000bhp at 6k but 640bhp at 9k i would hit 200mph.

So i can make up with tyres but i may need more than 640bhp to hit my target, hence the aim of 700bhp at around 30psi.

A completely stock engine(ie built by a guy on the mazda production line)with my turbo did 709bhp at 33psi and runs 9sec quarter miles so the power is avaliable

that way if 200mph is past my peak power slightly then it still should be above 640bhp.

this was from Rod about his old saff cosworth engine which was 750bhp on gas and did 201.6mph at that power

'On my last engine Peak Power was below 7.5k but held on to about 7.7k. We pulled 8.2k so was well past peak Power. BUT we could not pull the longer gearing so this was the best compromise'

So at 200mph he wasnt putting out the power people think he has because hes gone past peak power

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
Just for reference now the engine has done 900miles i took it to a dyno to see how the engine was doing.

running a very rich map(so power lost) running stock boost(10psi) pulled some timing aswell and it made 283bhp at 6900rpm.

This is 400rpm higher than stock and 30bhp more power, so at a very low boost running super rich(11:1 afr)

This shows that my ports are flowing well, id imagine with a bit of adjustment to the fuel to where the stock afr is sort the timing out another 20bhp could be gained, so thats 50bhp above stock at same boost

just need to do a compression test to check everything is bed in correctly and then start saving more money to start putting things together

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
since this is my thread, i thought id do a little rotary porting 101 if people are still reading.

to understand a rotary engine you have the imagine, how could i make my engine simpler, what things limit me when im making power(naturally asp)

Well first we look at cams, stock cams are normally pretty mild, with low lift and short duration, so, they dont allow the valves to open much or for long......doesnt allow much space to get that air in there does it.

So we change over to a more aggressive cam which does it....more power!

then we move onto the head, because yes the valves are nice and open but the air still needs to get down to them by passing down a small hole, increase the size of that hole(port) means we can more of that valuable air to the valves.

now from reading that you understand the basic principles of piston engine tuning.

Now a rotary isnt some magical engine run on leprechauns and peanut butter, it must follow the same rulls as a piston engine.

But how it does this well....it swaps all that for just a hole, thats right, the cams, valves, valve springs, head.

Now i wont go into detail on how a rotary works, ill just explain how to tune them.

Before reading anything else below i suggest you watch this as i found this explains how a rotary works very well so everybody should understand it
http://www.youtube.com/watch?v=oGrD7...eature=rela...


Ok now you have watched it ill continue on.

As you saw in the video, the rotor has 3 sides, to make it easier, ill call the first side, SIDE 1.
the port where the fuel/air comes in is opened by one end of the SIDE 1, the air/fuel comes in, then is closed off by the other end of SIDE 1.

So you have an opening and a closing, just like you do with a cam to open and close valves.

Now this below is a typical stock port, the one you find on standard rx7s



when the rotor moves to reveal the port(open) the first part that is opened is the long left hand side edge, the mixture comes into the chamber and then the other end of the rotor closes the port at the top horizontal edge as it rotates.

So by making the hole larger in different areas you can affect when the port will be open and also when it will be closed.

these are 2 pics of my templates over stock ports so you can see what i have done to my engine

this is my secondary port(ie big one to help with high rpm)

as you can see i am making it open earlier a little bit, if you go to far you get overlap so loose to much low down power, but then you can see i have increased it alot at the top of the port(closing) this is to help get the air into the engine, ie wait as long as possible before the port closes, this like duration on cams.

One last thing you should notice is the stock port has a flat top and mine is a curve, this is to help the engine make the power a little bit lower down and give me a wider torque curve, if it was straight it would close instantly instead of a lower close and a faster close means you make maximum power higher in the rpm.

Since the engine needs to be useful for many different things i found it would be best to not make a 10krpm screamer.


now this is my primary port, this is the one that the fuel goes down when in driving like miss daisy and generally pootling around.

Now because of i want the car to run around nicely on the street i want to keep this mild.

Now as you can see the out edge is ported much larger than the secondary port above, the reason for is the port is smaller than the other so i have more room to increase it without getting overlap.

if you compare the pictures apart from the length, they are the same width, showing that both ports now open and close at the same time.


Now thats the port timing done(like fitting cams) now because as you can see i have had to increase the size of the ports to get the timing right i have also allowed much more air to pass through because of there physical size....this is like porting out a head for it to flow more.

Pretty simple really, buy a dremel and a porting kit from b&q and do it yourself, does the same thing as porting a head and buying a set of expensive cams, valves, valve springs

turbotoaster

Original Poster:

655 posts

174 months

Tuesday 26th January 2010
quotequote all
well bit of a small random update, since i got the apexi ecu ive just celotaped it to where my pocket pc is on the left hand side of the gearstick, this was just to monitor is on friday while i top up with fuel and let the ecu learn the idle.

The issue was that it was so far away from my line of sight that i had to take my eyes well away from the road to monitor it, now after neally driving into a curb last night while watching my knock readings i decided its better to look for something to attach it to sooner rather than later.

Ill also need it for my top speed runs and i dont want to be looking away from the tarmac for that

So i theres the r magic power fc holder from japan but they are £50 and thats alot for just a piece of plastic, so i started looking at the commander and thought, well its the shape of a phone, why dont i just get a phone holder.

so i started searching the net for one, i found a few that attach to the windscreen but didnt fancy that as people might think its a sat nav and smash my car open when i go to tesco etc.

then i saw the ones that fit to your air vents, better i thought so i sat in the car and looked straight head to see if the vents were in my eye line, not quite.


so i looked at my dash, and thought where is the best place to put it, well i dont smoke and where the cigarette lighter would be good.

so i sat and made a little design on a scrap piece of paper and commited to making myself one during this week.

Anyway i was walking around tesco today and walked past the mobile phone part, decided to have a quick look and what do you know, they had the perfect thing.

Also as an added bonus they reduced them down from £6.84 to £1.99!!

So snapped it up and took it home.

first things first, cut of the little charger cable that i dont need.

where fag lighter is

attached commander to holder

plug into fag lighter and adjust height

check visability...seems good

turn lights on for night mode


a day full on win it seems.

anything that helps me stay in budget is a good day for me