Engine advice
Afternoon all.
I am from over the pond and looking for advice on my engine setup. My longterm goal is circa 350bhp. Now I know what to do to get that but I am being advised by people in the UK that's a silly goal, a torsen diff and 6 speed box will not last long at all and rebuilding the motor with forged internals is asking for trouble as it won't last long. They advise sticking this side of 280bhp and running a stock engine without opening it up! Is that true about the diff and box? I really don't understand how a rebuilt engine will not be up to the job. I can onlt think that these guys have had bad experience with poor built engines. I thought a well built forged engine would be almost bulletproof. I am a little lost and just wanted some further advise before I proceed. |
a DD with that power goal should not have issues with the 6-sp trans nor diff nor motor.
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Sorry, I should have said. It will be a 100% track car, stripped, made as light as possible etc.
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motor will be fine. trans and diff will need to be monitored. See how Savington is handling it.
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I don't know how anyone could say that a forged engine would be less reliable than stock, unless, as you pointed out, it was poorly built. A poorly built stock one would likewise be unreliable.
I would use billet oil pump gears and a good aftermarket harmonic damper. Edit: I think Sav is putting out 280-300 wheel hp on the track. |
Originally Posted by AdamL
(Post 682778)
Afternoon all.
I am from over the pond and looking for advice on my engine setup. My longterm goal is circa 350bhp. Now I know what to do to get that but I am being advised by people in the UK that's a silly goal, a torsen diff and 6 speed box will not last long at all and rebuilding the motor with forged internals is asking for trouble as it won't last long. They advise sticking this side of 280bhp and running a stock engine without opening it up! Is that true about the diff and box? I really don't understand how a rebuilt engine will not be up to the job. I can onlt think that these guys have had bad experience with poor built engines. I thought a well built forged engine would be almost bulletproof. I am a little lost and just wanted some further advise before I proceed. Build your motor with these and you should have no trouble at that power level: 949racing or m-tuned rods boundry engineering oil pump gears supertech or wiseco low comp pistons New quality water pump New timing belt w/ new tensioners New Felpro or oem seals all the way around
Originally Posted by AdamL
(Post 682778)
Is that true about the diff and box?
If you are driving it on the street you should be fine, but avoid doing too many launches on a drag strip if you don't know what you are doing as whele hop can hurt a torsen at those poer levels. Other than that they are pretty bullet proof. |
You have all more or less said what I thought. I didn't really believe what people were saying but after a few told me the same thing I did wonder what is so special about MX5 engines!
What is a harmonic damper? Thats a new one on me. I will be building the engine, I have built 3 different engines before but not a MX5. Block and head will be checked by machine shop. |
This or similar:
http://www.summitracing.com/parts/ATI-918522 At those power levels for track duty I would recommend one. Our engines have some harmonics issues that can effect reliability at higher RPMs and higher power levels. It is cheap insurance. +1 what RHarris said. |
Rharris is right. I've been tracking my car at 240whp with the 6-speed and it's fine but I'm very easy on shifts, soft with the clutch, and leave a lot of time on the table because of it...but I make it home every time.
I hope you have years and years of experience because a 250whp Miata is a handful, a 350whp car is a death-machine. |
Originally Posted by sixshooter
(Post 682801)
This or similar:
http://www.summitracing.com/parts/ATI-918522 At those power levels for track duty I would recommend one. Our engines have some harmonics issues that can effect reliability at higher RPMs and higher power levels. It is cheap insurance. |
I'd still build my motor for a 250rwhp track car.
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I am 29, soon to be 30. Had a TVR, 2 MR2 turbos(1 @ 250bhp and 1 @ 300),Elise....
Been on track in quick cars too and just want something that is always going to feel very fast. I don't want to build something that in a year I am bored of and want more power. I am sure many of you have been there. |
Originally Posted by AdamL
(Post 682809)
I am 29, soon to be 30. Had a TVR, 2 MR2 turbos(1 @ 250bhp and 1 @ 300),Elise....
I didn't mean to imply that you weren't a good driver, but 90% of people don't understand how fast a 250whp Miata goes around the track. As for the list of cars, 99% of this forum's track crew shit's all over that list every weekend, and we do it on less than 250whp, on our out-laps. Over 250whp on a track car is a losing battle and you better have a spare with you because you're on borrowed time. |
Hustler - only fair of you to ask. I can understand you asking too, there are far too many guys out there coming from a 1.4 engine and wanting a 300+bhp monster but not having a clue what that equates to in terms of speed. I have driven Caterhams and single seaters on track also so quick cars are not out of the norm for me.
Appreciate all the advice. Why do you say that "Over 250whp on a track car is a losing battle and you better have a spare with you because you're on borrowed time."? |
Originally Posted by AdamL
(Post 682817)
Hustler - only fair of you to ask. I can understand you asking too, there are far too many guys out there coming from a 1.4 engine and wanting a 300+bhp monster but not having a clue what that equates to in terms of speed. I have driven Caterhams and single seaters on track also so quick cars are not out of the norm for me.
Appreciate all the advice. Why do you say that "Over 250whp on a track car is a losing battle and you better have a spare with you because you're on borrowed time."? |
What is your spec Hustler?
Did I read somewhere you are running ebay China rods? It sounds like 250 at the wheels sounds like the upper limit of safe unless I win the Lottery, haha. At least that gives me a goal to build my spec around and go parts hunting. At the moment I am going to strip, clean, hone my 1.8 engine and put back together with a 99 head and run it N/A till the turbo engine is built and ready to pop in. By this time I will have the rest of the car sorted and ready for the power hike. |
Originally Posted by AdamL
(Post 682817)
Why do you say that "[I]Over 250whp on a track car is a losing battle
When it breaks loose (and it easily does in the lower 3 gears, and even more easily mid corner) with no electronic gizmos or traction control and a short wheel base its a job and a half straightening it back out without slowing down dramatically and ( I assume ) losing lots of time. Just my .02 |
No I havent driven a 350bhp MX5 but I have driven enough that I can imagine what it's like. I am quite happy in a slide and comfortable to control it. People always moan how dangerous the MR2 is in the dry when pushed and leathal in the wet. I never found this, yes it would easily stick the back end out but it was always precdictable and easy to control.
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I would get a good balancer. At worst, you will have to remove the sway bar to pull the balancer if you had to. It is main and rod bearing insurance.
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You sound like you know your way around a track and have more skill than the average track guys here so by all means shoot for 350whp.
Just take lots of pics and videos along the way:) |
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