opinions sought re small 12cyl twin turbo

[jimbob82]

Max_Torque said:

I suspect the engine would never run, or only for a few seconds before failure however.

Would you care to elaborate this theory please? I don't see it being destroyed that quickly if everything is done right...

as for the costing, £400k seems a little on the crazy side of what I have costed so far.

I agree there are ALOT of parts to this engine...

12 pistons and rods
12 cylinder liners
48 valves, springs, caps, rockers, guides, seats.
4 rocker shafts
4 camshafts
1 billet crank
24 Big end shells
14 Main bearing shells
2 identical crankcases (probably cast this so just needs final machining)
2 identical split heads
2 identical blocks (probably cast this so just needs final machining)
2 identical cam covers
2 exhaust manifolds (make these myself)
2 inlet manifolds (make these myself)
1 sump pan (make this myself)
1 or 2 water pumps - depending on how I decide to do it - might go for electric though (saves a little on machining)
1 billet flywheel
1 clutch (twin plate)
1 release bearing and associated cylinders
2 turbos
12 piston cooling jets
2 timing chains
slippers and tensioners
oil pump (purchase a good generic aftermarket one - whichever fits the bill best)
12 injectors
fuel tank and pump (make fuel tank myself)

not forgetting:
2 headgaskets
14 Main bolts
28 head bolts
2 thermostats & housings - or 1 common thermostat but i think 2 is better (1 per side)
12 spark plugs
HT leads/coil packs depending on which I decide on being best
oil and a filter
other associated gaskets
front and rear main seals and housings
front timing chain covers
more miscellaneous bolts/nuts

and balancing the engine

not a bad little shopping list really. I can go and pick it all up, who's gonna pay for it?

---

In answer to some of the questions,

@AER - I appreciate all constructive input and criticism and in answer to some of the points you raised,

I don't think the surface to volume ratio needs to be considered with too much vigor due to me only running a CR of 8.5/9:1. not like i'm going F1 spec with 13:1 and N/A for that kind of power.

reason I want 12 cylinders and low cc is: 12 cylinders at 2 litre means less stress per cylinder as opposed to a 4cyl @ the same rpm and power output, crank is 7 main bearing so no different to a conventional V12 but the HOP will be more balanced between these mains.

Re the firing order, yes I agree. I was considering going along the lines of the jaguar v12 firing order at first but oweing to the fact mine is completely different, I don't think it would pan out.

The idea is to use the engine in a circuit racing car similar to an atom/caterham - no road use, just track.

With regard to "schwerpunkt", If I package it well it "should" have a lower COG than a V8 or a V12, unles they're 180 degree V's ofcourse Everything is pretty much horizontally inline with the crankshaft and moving on the same horizontal plane.

Bladerider: thanks for the input, I think the GT28 is too big - the exhaust gas flow won't spool it up quick enough unless i go VGT or get a specific housing made up (hybrid), accoding to PFEA it won spool until about 9000rpm whereas the gt25r is the best match I can find so far spooling at 6000rpm and holding it right through to 12000rpm @14psi. I'll definately look at contacting the guys at Turbo Dynamics, Thanks.

@dblack1: I suppose coolness is a factor yes, but who doesn't like the sound of 12 cylinders going over 9000rpm? and because I believe I can, if you believe you can do something I think you should do it to the best of your ability, if it doesn't work out you put it down to experience and re-evaluate

@Evoluzione: i am speccing the turbos to the engine BEFORE building it because it's the best way. If I build the engine then spec the turbos for it I will likely have to change something which would cost more. better to do it right first time than have to stepback and redo something.

Edited by jimbob82 on Tuesday 12th February 21:05

[anonymous-user]

jimbob82 said:

Max_Torque said:

I suspect the engine would never run, or only for a few seconds before failure however.

Would you care to elaborate this theory please? I don't see it being destroyed that quickly if everything is done right...

If you had said:


"I have spent 30 years designing and developing race engines from scratch, and i have a £200k budget" then yes, there is a chance that a completely bespoke one off engine might run properly the first time and not pick up a ring, scuff a bore, spin a bearing, suffer from oil starvation, experience valve float, have a thermal failure of parts of the cylinder head, have a TV failure of the crank, or about a thousand other things that can, and do, go wrong with bespoke engines.

I should know, i've broken enough of them............. Anyway, i wish you the best of luck with this project!


regarding CofG, there is no point whatsoever in having the engines CofG very low if you can't package the engine low in the chassis because for example you have to fit an exhaust system underneath. As you can see, there are exactly no F1 engines using flat layouts for this very reason (and the only production car that does has a high CofG due to such package limitations.

I assume you have a plan to accomodate the necessary bank stagger and deal with stuff like timing drive to identical head castings/machinings etc?

[jimbob82]

Max_Torque said:

If you had said:


"I have spent 30 years designing and developing race engines from scratch, and i have a £200k budget" then yes, there is a chance that a completely bespoke one off engine might run properly the first time and not pick up a ring, scuff a bore, spin a bearing, suffer from oil starvation, experience valve float, have a thermal failure of parts of the cylinder head, have a TV failure of the crank, or about a thousand other things that can, and do, go wrong with bespoke engines.

I should know, i've broken enough of them............. Anyway, i wish you the best of luck with this project!


regarding CofG, there is no point whatsoever in having the engines CofG very low if you can't package the engine low in the chassis because for example you have to fit an exhaust system underneath. As you can see, there are exactly no F1 engines using flat layouts for this very reason (and the only production car that does has a high CofG due to such package limitations.

I assume you have a plan to accomodate the necessary bank stagger and deal with stuff like timing drive to identical head castings/machinings etc?

OK thanks for the input. I appreciate what your saying but everyone has to start somewhere no? I know any mechanical part can fail no matter how well it's made, F1 engines fail and they spend silly money on those things. I will do my best to limit the factors that can cause such failures - as all engine builders/tuners do but things can still fail for no apparent reason.

Thanks for the best wishes

re bank stagger:

I have that sorted yes.

[-Bladerider-]

Well,

I suggested a 28r as it can be specced with largish housing whereas I didnt see any on the 25 although there is very little diference on them on 4 cylinder 2.0 cars from experience. And given you were aiming for over 300bhp/bank I think you will struggle to do that without choking the engine on a 25 frame unless you are hapopy to go to very high levels opf boost which will bring a host of other issues with it.

F1 turbos ran at upto 5bar boost and were as laggy as feck but only had a single turbo !!

I understand why you want a 12 but i think aiming for 60x60 may come with costs and piston stresses that could be avoided at a much lower cost perhaps by using mass produced pistons and rods already designed fror the sort of revs you are talking about - basically look at some bike engine and choose what suits - maybe cbr600 or old gsxr750 pistons as these fall either side of your 2.0 target for capacity.

This would also give you a potential crank design to reverse engineer into your configuration.

Oh and for the doubters then maybe lookup BRM V16 for sound of something truly special from back before computers let alone ECU's that is much more radical than this project.

Also remember the italian guy who built his own flat 12 ferrari and pistins etc from scratch at home with no formal training at all.

Anything is possible.

[Nick1point9]

jimbob82 said:

performance trends engine analyzer that's how i came up with the approx 640bhp @ 12,000rpm

a lot of money agreed, about 40k covers it, which if you consider all the machining and materials involved isn't THAT expensive for a 1 off.

I suppose a V engine would be simpler but that's the norm IMO, I was looking to do something a bit more...i suppose crazy lol

I appreciate the comments/critics, all taken on board so far.

anyone have any input on the original question re turbos?

R&D obviously isn't your thing... Do you really think the first engine you make will work well? With highly skilled engineering you might have something that works well after attempt 4 or 5, so absolutely no way under the sun you'll get what you want for £40k. Oh and wait until you break one.

[Tango13]

AER said:

BTW, I was told by someone that might know, that of the 12-factorial (or whatever it is) different firing orders available of a 12-cylinder engine, there are only two that will actually work without tearing the engine apart...

There is an appendix at the end of Karl Ludvigsens book on the V12 that talks purely about firing orders.

According to the autor of the appendix, Dan Whitney there are 16 usable/practicle firing orders of which nine have been used at one point or another.

ETA

dblack1 said:

more cylinders don't have anything to do with how high a motor can rev. a 4 cyl can rev up to 15k rpms, in fact, look at sport bike motors, many of them rev up to 9k+. Most motors have a limiter much lower (and are tuned to operate at lower revs) to make the motor more reliable, cheaper to produce and/or more fuel efficient. 12 cyls do sound wicked tho, but the sound can be emulated by smaller motors (as proved by both nissan and yamaha).

Little bit behind the times there 13,000rpm for a 1 litre production bike is normal these days and in the late 80's early 90's a Japanese market only CBR250 would rev to 19,000rpm!

Edited by Tango13 on Wednesday 13th February 09:07

[The Black Flash]

-Bladerider- said:

Oh and for the doubters then maybe lookup BRM V16 for sound of something truly special from back before computers let alone ECU's that is much more radical than this project.

That would be the one which kept breaking and was generally massively unreliable, right? Not a great example.;)
My favourite sounding engine, ever, though.

[SuperchargedVR6]

AER said:

Why do you think it will achieve this?

The ideal engine for a light-weight, high-revving, silly-power engine is probably the four cylinder. Twelve cylinders gets you a load more friction, a heavier crankshaft that's also long and very floppy, eight more inlet and exhaust pipes to plumb as well as the associated valves, injectors, lifters, lobes and sundry bits. Dividing the total combustion chamber volume by 12 also degrades your surface-to-volume ratio, effectively limiting your maximum compression ratio.

I was kind of thinking along those lines.

I pondered on this last night in bed (sad I know) and wondered why 12 cylinders would be required to get 640hp from 2 litres? Is it a hp per cylinder thing or just a mega revs thing?

[jimbob82]

SuperchargedVR6 said:

I pondered on this last night in bed (sad I know) and wondered why 12 cylinders would be required to get 640hp from 2 litres? Is it a hp per cylinder thing or just a mega revs thing?

12 cylinders aren't strictly "required" for that HP. 12 vs 4 at the same output means less stress per piston.

12 cylinders @ 640hp = approx 50HP per piston
vs
4 cylinders @640hp = approx 160HP per piston

with more pistons and shorter stroke it will rev quicker aswell and lighter flywheel can be used

Nick1point9 said:

R&D obviously isn't your thing... Do you really think the first engine you make will work well? With highly skilled engineering you might have something that works well after attempt 4 or 5, so absolutely no way under the sun you'll get what you want for £40k. Oh and wait until you break one.

[SuperchargedVR6]

jimbob82 said:

SuperchargedVR6 said:

I pondered on this last night in bed (sad I know) and wondered why 12 cylinders would be required to get 640hp from 2 litres? Is it a hp per cylinder thing or just a mega revs thing?

12 cylinders aren't strictly "required" for that HP. 12 vs 4 at the same output means less stress per piston.

12 cylinders @ 640hp = approx 50HP per piston
vs
4 cylinders @640hp = approx 160HP per piston

with more pistons and shorter stroke it will rev quicker aswell and lighter flywheel can be used

That makes sense to me!

I would imagine 160hp x 4 would be harder to achieve than 50hp x 12?

How about a nice little flat 8 @ 75hp x 8?

Good luck with it sir, sounds like an interesting project! Keep us posted.

[chuntington101]

Considering 2.0ltr motors pushing out 1000bhp on good fuel are out there (look at the EVO guys for examples) then i cant see 650+bhp on normal fule being any issue for a 2.0ltr 4pot motor. Anyone know whats the most a Duratec is pushing out these days? I think there ws a Ford Feiesta Puikes Peak car that was running approx 850bhp throguh a Duratec engine. The GM 2.0 and 2.2ltr Ecotec engines have pushed well over 1000bhp (again on good fuel) so could be another option.

Chris.

[-Bladerider-]

I dont think sensibleness is what is wanted !! lol

I think "extreme" "unique" and "because its a challenge" are the prime buzzwords !!

If you genuinely wanted to do this on a realistic budget with a genuine chance of success first time with the best possible result them you would obviously look at a V8 made from {insert jap brand here} 1 litre bike piston and rod design mated to a custom crank, this allows use of head and cam designs that are proven to work and all thats tricky to get perfect would be the turbos. Once turbo specs are right you can reverse spec the combustion chambers and piston tops and maybe stringer rods, knock the revs down to 12,000 to allow for extra stresses stronger pistons and heavier rods will incur and hey presto you have a turbo'd lower capacity version of the "Hayabusa v8" used by Arial and Caparro !!

J.

[SuperchargedVR6]

chuntington101 said:

Considering 2.0ltr motors pushing out 1000bhp on good fuel are out there (look at the EVO guys for examples) then i cant see 650+bhp on normal fule being any issue for a 2.0ltr 4pot motor. Anyone know whats the most a Duratec is pushing out these days? I think there ws a Ford Feiesta Puikes Peak car that was running approx 850bhp throguh a Duratec engine. The GM 2.0 and 2.2ltr Ecotec engines have pushed well over 1000bhp (again on good fuel) so could be another option.

Chris.

I was thinking in terms of normally aspirated. I completely forgot about the turbo element!

The last time I flicked through the net about Duratecs, I'm sure I saw a 320hp n'asp one. Standalone, ITBs, cams, the lot. One of those with a turbo would be impressive I reckon.

[jimbob82]

-Bladerider- said:

I dont think sensibleness is what is wanted !! lol

I think "extreme" "unique" and "because its a challenge" are the prime buzzwords !!

lol, nail on the head

SuperchargedVR6 said:

The last time I flicked through the net about Duratecs, I'm sure I saw a 320hp n'asp one. Standalone, ITBs, cams, the lot. One of those with a turbo would be impressive I reckon.

yeh the ecotecs can do 300bhp N/A too, seen one recently being fitted into a mk2 escort.

if you turbocharged one of those without modifying them you'd highly likely blow the thing to bits.

from that 320bhp you quoted, you'll probably find it's developing that power somewhere around or between 7k-9krpm depending on how they've set it up. that's why F1 engines run at 19krpm, if you want more power without turbocharging or increasing displacement you have to rev higher. higher revs = higher piston speeds and piston acceleration which in turn puts more pull on the inlet ports thus increasing VE% and developing more power. This isn't as much a factor when turbocharging because the turbo is always FORCING the air in, (when it's operating at boost level, before boosting it's lagging because it can't supply the amount of air required). but you more than likely know this

[Evoluzione]

jimbob82 said:

@Evoluzione: i am speccing the turbos to the engine BEFORE building it because it's the best way. If I build the engine then spec the turbos for it I will likely have to change something which would cost more. better to do it right first time than have to stepback and redo something.

Edited by jimbob82 on Tuesday 12th February 21:05

Sorry I disagree, at this point in time you don't need to spec a particular turbo.

[Nick1point9]

If you don't mind me asking, what is your professional background?

[chuntington101]

jimbob82 said:

SuperchargedVR6 said:

The last time I flicked through the net about Duratecs, I'm sure I saw a 320hp n'asp one. Standalone, ITBs, cams, the lot. One of those with a turbo would be impressive I reckon.

yeh the ecotecs can do 300bhp N/A too, seen one recently being fitted into a mk2 escort.

if you turbocharged one of those without modifying them you'd highly likely blow the thing to bits.

from that 320bhp you quoted, you'll probably find it's developing that power somewhere around or between 7k-9krpm depending on how they've set it up. that's why F1 engines run at 19krpm, if you want more power without turbocharging or increasing displacement you have to rev higher. higher revs = higher piston speeds and piston acceleration which in turn puts more pull on the inlet ports thus increasing VE% and developing more power. This isn't as much a factor when turbocharging because the turbo is always FORCING the air in, (when it's operating at boost level, before boosting it's lagging because it can't supply the amount of air required). but you more than likely know this

Obviously running much boost through a 13:1 comp ratio engine isn't going to be the best. However drop the comp to 10:1 and fit some more turbo freindly cams and hay-prest you have a stonking turbo motor.

Granted it problably wont support 45psi + and 1000bhp but it should easily make 650bhp on the right turbo (GT35rs) with a reasonable power band and should have good throttle responce esp with the ITBs.

Chris.

[jimbob82]

Nick1point9 said:

If you don't mind me asking, what is your professional background?

^^ THIS



























is something I could never do

I've been a mechanic for about 15 years, engine rebuilds mainly but also general mechanics. also do body repair and light fabrication. my business partner has been a mechanic for over 50 years (used to work for rolls royce, jaguar, aston martin), he was tuning jags in the 60's & 70's and he's taught me most of what i know. the rest I have gleened from books and other people.

Edited by jimbob82 on Thursday 14th February 11:09

[andygtt]

Im always doing things professionals think I am mad attempting in my garage... however even I think designing and building an engine from scratch is an epic task to do right.

Worth mentioning that some of the people I have seen replying on here actually do this kind of thing for a living... so take heed of their advice.

The areas I would be concerned about in the design would be hot spots and oiling... not simple to avoid I expect... also how are you going to design out the chance of the engine producing a harmonic at any rev that destroys itself?

Id be basing the design around something existing which is what most of the bespoke engines I have seen have done... ie take a bike engine and use the heads on a new block and crank.

Good luck and keep us informed of progress.

[T70RPM]

All good entertaining stuff.

"2 identical crankcases (probably cast this so just needs final machining)
2 identical split heads
2 identical blocks (probably cast this so just needs final machining)"

I don't want to p*ss on your bonfire, but having just cast my own engine block, the cost for the pattern work alone will be from £30 to £80K before you even cast a part. (best spend the higher amount too, if you actually want it to work.)

I will watch your project develop with interest.....