Some questions about NA versus Turbo versus Supercharged 5
Discussion
I thought the '5 had issues with stability at high speeds? I always fancied one of those chin spoilers, they're subtle but butch the car up a lot and apparently really help with high speed stability. Sadly even the knock-offs are 200 quid plus 
Personally the idea of doing speeds like that in a Mk.1 terrifies me, I'm not very comfortable in mine doing much over 80 on the motorway, 70-75 feels a much more natural cruising speed.
Personally the idea of doing speeds like that in a Mk.1 terrifies me, I'm not very comfortable in mine doing much over 80 on the motorway, 70-75 feels a much more natural cruising speed.
The question of gear-limited top speeds is slightly complicated by there being 2 different gearboxes and 4 different diff ratios available in different years.
The longest you could go would be 6th in a 6 speed (0.843:1) with a 3.636:1 diff which on 195/50-15"s would give a gear limited top of 149.9mph (assuming a 7k rev limit). It can be as low as 131mph (5th of 0.814:1 and 4.3:1 diff).
The longest you could go would be 6th in a 6 speed (0.843:1) with a 3.636:1 diff which on 195/50-15"s would give a gear limited top of 149.9mph (assuming a 7k rev limit). It can be as low as 131mph (5th of 0.814:1 and 4.3:1 diff).
LexSport said:
The longest you could go would be 6th in a 6 speed (0.843:1) with a 3.636:1 diff which on 195/50-15"s would give a gear limited top of 149.9mph (assuming a 7k rev limit).
Nah - Mk2.5 Sport 6-speed are all geared for 160mph at 7000rpm.Mk2.5 has a more aerodynamic front with a small chin-spoiler under the bumper and is very stable at high speeds.
To be honest I have absolutely no idea what speed it will pull to - all I know is that I accelerated from 80mph in 6th and just let it run. It didn't let up at all and was still accelerating strongly at 150. I only stopped then because the speedo stops at 150 so there is no point going any faster
As for speedo accuracy - that's a different matter. I know mine is actually pretty much spot on at motorway cruising speeds due to having 17" wheels with 205/40/17 tyres (speedo over-reads by about 2% with stock wheel/tyre sizes) but at 150? Who knows???
It's all academic really as I don't suppose I'll ever have the chance to go near those sorts of speeds unless I take a trip to an unrestricted autobahn or a PH VMax event (but I doubt 1 mile would be long enough).
Edited by MX-5 Lazza on Saturday 1st December 23:45
hello all,
just to add my bit to this conversation.
i drive a mk2.5 begi turbo kitted 5 running 10psi that has recently been dyno'd at 243bhp and tbh i was glad that the dyno operator commented on the torque characteristics of my engine (ie completely linear) because i just don't associate with the stereotype often perpetuated by folks on the internet of turbolag. my car drives like a very powerful NA car and tbh i couldn't be happier with it, my wife drives it every bit as much as me and she has never been caught out either.
I think you need to put stereotypes aside because the internet is full of them and make your own mind up.
To answer the question earlier, turbo's are much better bang for buck than SC's, area under the curve included. The only benefit that SC's have power wise is from tickover to 2000rpm which is largely irrelevant for 'spirited driving'.
ps, can anyone host a copy of my dyno sheet so i can post it up to demonstrate the torque 'line'
Greg
just to add my bit to this conversation.
i drive a mk2.5 begi turbo kitted 5 running 10psi that has recently been dyno'd at 243bhp and tbh i was glad that the dyno operator commented on the torque characteristics of my engine (ie completely linear) because i just don't associate with the stereotype often perpetuated by folks on the internet of turbolag. my car drives like a very powerful NA car and tbh i couldn't be happier with it, my wife drives it every bit as much as me and she has never been caught out either.
I think you need to put stereotypes aside because the internet is full of them and make your own mind up.
To answer the question earlier, turbo's are much better bang for buck than SC's, area under the curve included. The only benefit that SC's have power wise is from tickover to 2000rpm which is largely irrelevant for 'spirited driving'.
ps, can anyone host a copy of my dyno sheet so i can post it up to demonstrate the torque 'line'
Greg
Hi Greg
Good to have your input - it's always good to have all opinions, especially when they are based on personal experience
The point I was making though is that a base level (£1.5k-£2k)turbo won't have a nice long flat torque curve. For that you need a full-flowing exhaust apart from any other changes. A similar level SC won't be affected too much by the exhaust.
Of course if you are prepared to spend the money on a full exhaust system & turbo downpipe (as well as the fuelling & tuning which is needed for either choice) then a turbo can indeed give you very big numbers and a good spread of torque.
Good to have your input - it's always good to have all opinions, especially when they are based on personal experience
The point I was making though is that a base level (£1.5k-£2k)turbo won't have a nice long flat torque curve. For that you need a full-flowing exhaust apart from any other changes. A similar level SC won't be affected too much by the exhaust.
Of course if you are prepared to spend the money on a full exhaust system & turbo downpipe (as well as the fuelling & tuning which is needed for either choice) then a turbo can indeed give you very big numbers and a good spread of torque.
Gents, excellent topic, some, err quite a few questions if I may.
I've read most that I can find, but am still a bit puzzled on the huge variety of kits out there & im somewhat bewildered by it all, pretty much what I 'think' ive learnt is, if on a 1.6 then a 1.8 clutch & flywheel & lsd to cope with the grunt is best, & other than that all I can think is perhaps the base turbo or supercharged kits no intercooler etc that are 150/160bhp area? are not quite going to give me what im after, which is 200bhp ton area as a gude minimum? & even intercooled cars vary a lot with very difernt boost levels.
I'm after is a mk1 mainly for price reasons, but also weight, cost wise I'm really looking at something already done, to the spec im really after, as from my other past cars im very well aware of what it costs to do it all from a base car & there seems to be quite a bit of choice out there at the mo at quite different price levels.
Reliabilty is key for me, it will be driven flat out on track a lot, so rather have tad less mumbo for less going bang, or ripping gearboxes or difs apart risks & massive lag really not what im after either, been there done that on other cars, not a great fan.
Do any guys do fairly hard track use on FI Mx's? I dont mean once a yr wobble round but say 10 events a year & what wears etc.
So my confusion is only compounded buy a few ads, what on earth is what out of this little lot??
Engine-
HKS T25 Turbo@7psi
Cosworth Intercooler
Greddy Emanage fuel controller
Greddy Profec E-01 boost controller
Greddy turbo Timer
Spec Stage 2 Clutch
FM Turbo Dual exit stainless exhaust
PiperX Induction air filter.
(ad quotes 180bhp/163lbft)
Engine:
Garrett GT2560R water-cooled ball bearing turbo
15" x 8" x 3" FM intercooler
2.0" ID - 2.5" ID pipes from compressor to intercooler
2.5" ID pipes from intercooler to throttle body
Ductile iron manifold
All intake pipes either formed silicone or polished stainless steel
Cold air intake setup using K&N air filter
440 cc/min RC injectors
Modified fuel rail: Fuel input double tapped for even fuel pressure
Blow off valve
FM Link replacement ECU with electronic boost control, knock sensor, and air temperature sensor included. Also Air flow meter is replaced with MAP sensor to ensure there is minimal intake restriction. ECU includes glove box key pad
Drivetrain:
ACT extreme clutch
Lightened flywheel
Exhaust:
FM single exit stainless steel exhaust. 2.5" pipe with 3" tail pipe (From CAT back)
FM high flow CAT
FM mild steel down pipe
(ad quotes 220bhp)
1.6L engine,.
Spec:
MAZDAPSEED 1.8 Supercharged MX5 190+bhp. This is not you everyday bolt on supercharger kit, this is a factory fitted mazdaspeed kit,
1993, 1600cc,
Factory Mazdaspeed Supercharged (B Spec)
Lots of questions, sorry, but any help & pointers greatly appreciated
I've read most that I can find, but am still a bit puzzled on the huge variety of kits out there & im somewhat bewildered by it all, pretty much what I 'think' ive learnt is, if on a 1.6 then a 1.8 clutch & flywheel & lsd to cope with the grunt is best, & other than that all I can think is perhaps the base turbo or supercharged kits no intercooler etc that are 150/160bhp area? are not quite going to give me what im after, which is 200bhp ton area as a gude minimum? & even intercooled cars vary a lot with very difernt boost levels.
I'm after is a mk1 mainly for price reasons, but also weight, cost wise I'm really looking at something already done, to the spec im really after, as from my other past cars im very well aware of what it costs to do it all from a base car & there seems to be quite a bit of choice out there at the mo at quite different price levels.
Reliabilty is key for me, it will be driven flat out on track a lot, so rather have tad less mumbo for less going bang, or ripping gearboxes or difs apart risks & massive lag really not what im after either, been there done that on other cars, not a great fan.
Do any guys do fairly hard track use on FI Mx's? I dont mean once a yr wobble round but say 10 events a year & what wears etc.
So my confusion is only compounded buy a few ads, what on earth is what out of this little lot??
Engine-
HKS T25 Turbo@7psi
Cosworth Intercooler
Greddy Emanage fuel controller
Greddy Profec E-01 boost controller
Greddy turbo Timer
Spec Stage 2 Clutch
FM Turbo Dual exit stainless exhaust
PiperX Induction air filter.
(ad quotes 180bhp/163lbft)
Engine:
Garrett GT2560R water-cooled ball bearing turbo
15" x 8" x 3" FM intercooler
2.0" ID - 2.5" ID pipes from compressor to intercooler
2.5" ID pipes from intercooler to throttle body
Ductile iron manifold
All intake pipes either formed silicone or polished stainless steel
Cold air intake setup using K&N air filter
440 cc/min RC injectors
Modified fuel rail: Fuel input double tapped for even fuel pressure
Blow off valve
FM Link replacement ECU with electronic boost control, knock sensor, and air temperature sensor included. Also Air flow meter is replaced with MAP sensor to ensure there is minimal intake restriction. ECU includes glove box key pad
Drivetrain:
ACT extreme clutch
Lightened flywheel
Exhaust:
FM single exit stainless steel exhaust. 2.5" pipe with 3" tail pipe (From CAT back)
FM high flow CAT
FM mild steel down pipe
(ad quotes 220bhp)
1.6L engine,.
Spec:
- Greddy Turbo (12 psi)
- Starion Intercooler
- 440cc Injectors
- FM Link ECU
- FM full SS Exhaust
- Mazda Racing downpipe
- K&N Airfilter
- 1.8 Spec 2 clutch
MAZDAPSEED 1.8 Supercharged MX5 190+bhp. This is not you everyday bolt on supercharger kit, this is a factory fitted mazdaspeed kit,
1993, 1600cc,
Factory Mazdaspeed Supercharged (B Spec)
Lots of questions, sorry, but any help & pointers greatly appreciated
Edited by iguana on Tuesday 4th December 00:34
there's no reason that a well tuned turbo would be any less reliable than an s/c - there are definitely some that are tracked often, but afaik, not many at the 200bhp mark, for whatever reason...
as for the list of stuff, what do you need to know? FM stands for Flyin' Miata, a major tuning company out of the states. get yourself onto www.mx5nutz.com/forum for lots of advice about charging the 5 (everything on those lists has been done by guys and girls on there). unfortunately i don't know much about the mazdaspeed charger...
as for the list of stuff, what do you need to know? FM stands for Flyin' Miata, a major tuning company out of the states. get yourself onto www.mx5nutz.com/forum for lots of advice about charging the 5 (everything on those lists has been done by guys and girls on there). unfortunately i don't know much about the mazdaspeed charger...
Edited by skinny on Tuesday 4th December 09:39
Phil @ P5 has tested one of those. Rather than combining the best parts of super/turbo chargers they actually combine the worst traits instead i.e. low boot at low revs and running out of steam at higher revs. They have their place but not on a Mk1/2/2.5 MX-5 where there are many tried & tested FI solutions.
They might be good on a Mk3 where space is restricted and boost levels need to be reined back a bit.
They might be good on a Mk3 where space is restricted and boost levels need to be reined back a bit.
not true they run them on Toyota and Honda k20 engines up to 10000rpm the are perfect for modern day engines the can run inlet speeds of 120.000rpm have a vast
range of sizes. example Toyota 20valve engine 238bhp run to 8800rpm made on 8psi
you do not have the heat problems. as to drivabilty thats just a mapping issue not
a supercharger. Honda K20 racer 2.bar 435bhp @9200rpm.
range of sizes. example Toyota 20valve engine 238bhp run to 8800rpm made on 8psi
you do not have the heat problems. as to drivabilty thats just a mapping issue not
a supercharger. Honda K20 racer 2.bar 435bhp @9200rpm.
Have a look at the site, there are so many diffrent Combinations, that it may need diffrent pully ratios and remember that you could also control boost with waste gate.or it could be you have incorrect inlet housing size.the supercharger
does not no or care whether it a mk1 or Mk3 it a pump.
does not no or care whether it a mk1 or Mk3 it a pump.
Boost on a Mk3 needs to be limited otherwise the engine will break.
Will a wastegate work? I'm not so sure. With a turbo, when you lift off the throttle the wastegate opens and dumps the excess boost and with the throttle off the exhaust stops spinning the turbo and the boost stops being created. With a belt driven supercharger the boost continues to be created with the throttle off because it's driven by engine speed. This is why superchargers don't have wastegates. I can't see any reason why a Rotrex would be any different.
Will a wastegate work? I'm not so sure. With a turbo, when you lift off the throttle the wastegate opens and dumps the excess boost and with the throttle off the exhaust stops spinning the turbo and the boost stops being created. With a belt driven supercharger the boost continues to be created with the throttle off because it's driven by engine speed. This is why superchargers don't have wastegates. I can't see any reason why a Rotrex would be any different.
No it doesn't. A dump valve dumps excess boost (used to stop the compressor stalling on a sudden increase in pressure when the throttle is closed). A wastegate diverts the exhaust gasses away from the exhaust turbine and straight into the downpipe to stop spinning up the turbine and generating the boost in the first place. A wastegate wouldn't exist on a Rotrex supercharger as there is no exhaust turbine. I am unaware of a dump valve that can be calibrated well enough to allow it to bleed off excess pressure over a specified limit.
Edited by anonymous-user on Thursday 6th December 09:50
interestingly, I had an NA MK1 1.6 turbo, which I got Turbo'd. The thing was, they didn't have any replacement ECU's at the time - so they just permanently retarted the timing and off I went. The change between on/off boost was quite scary (but in a kind of good way!!) if you had your foot on the floor - it just took off at about 4K revs. I also had a sports (ASBO) exhaust fitted at the same time to help the turbo to spool quicker.
I took it in for a service and they fitted a BIPES ecu at the same time. Now it's much smoother - not that I've driven one, but much more what I'd imagine a SC car to be like.
Still think that I'm going to swap it for an MR2 turbo though (mostly as I fancy a change for no good reason!)
my only advice would be that I would have bought one with the bits already done - it gets very expensive doing the bits yourself. I know that people are always a little wary of buying already modded cars ( I was) - but I think that with the benifit of 20:20 hindsight, going the route i did was a mistake.
Cheers
-ace
I took it in for a service and they fitted a BIPES ecu at the same time. Now it's much smoother - not that I've driven one, but much more what I'd imagine a SC car to be like.
Still think that I'm going to swap it for an MR2 turbo though (mostly as I fancy a change for no good reason!)
my only advice would be that I would have bought one with the bits already done - it gets very expensive doing the bits yourself. I know that people are always a little wary of buying already modded cars ( I was) - but I think that with the benifit of 20:20 hindsight, going the route i did was a mistake.
Cheers
-ace
IIRC BIPES is a timing controller. Sounds like you've got an AFPR fitted which will increase the fuel pressure to push more fuel through the standard injector opening times. The BIPES will then let you get some timing back at lower boost levels so the engine isn't as sluggish when off boost.
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