whats needed for higher torque than power in re build?

Ok, I am about to have our engine re built for our mk2 race car....circuit racer doing 1hr races.
It is running on ABF with dth jenveys, omex ecu, schrick cams and 4-1 manifold etc at present.
Due to regulations we can only raise the power at wheels to around 175bhp at present 159 ( on the dyno that counts...some read 170!)
So we need to gain a bit more power which I think will come with the head work we are going to get CNC heads to do and bespoke cams.
Now as title states we want to build for Torque as there is no limit on this. so instead of building for 175bhp engine and the torque being what ever...we want to build to 175bhp and have massive torque.
This will mean I am sure a slightly odd or unconventional build? but will assist us massively come race days.
Also would be happy to over build engine so can be tuned down on dyno so OUR maximum power comes a little lower with a flat top if that makes sense? ie we can hit top power and keep it while still revving up the range assisting us when we change gear by closing the gap. Does that make sense?
Also want to make reliable as poss so want to have built to rev more than we need.
I will be looking for a reputable builder to undertake the work( any recommendations) who I am sure will have there own ideas but I would appreciate advise from all angles really to throw the balls in the air.

cheers

 

Bear in mind, the box I'm building you will be built is a very short ratio/final drive which will be beneficial with high rpm.

 

prity much unlimited .
basically runs on a bhp per tonne basis hence the give or take 175bhp maximum ( car is always getting lighter...down to around 900kgs now..but add me and we are back up to 1000kg )
so by enginering the engine to this maximum but manipulating the build for torque we should be getting the absolute best we can .
If I move up a class then I can go to around 200bhp but again would want torque to be more.

 

surely I carnt have too much of a good thing????

 

Looking forward to getting the 020 installed Mart.
Glad we didn't rush it for this weekend as had cambelt go on us in qualifiying and missed the start of race by 5 mins after manic fixit session ( found it completely fraid but hadn't gone fully luckily)......

 

Lower down fatter torque usually means less cam, but less cam means peak power at lower revs. My favourite FD at the minute is a 4,2 on a 0.91 fifth. But
you need to find your fastest track and do the sums to make sure you aren't on the limiter in top too early on the longest straight
IMO
Jon

 

wouldn't crank/piston/bore combination have something to with the characteristics I am after also?

 

If regs are unlimited, turbos make a lot more torque.

 

Less aggressive camshaft I think would be the best way to control your profile. Build the engine for max torque is the same for max power as hp is torque.

If you want low down torque you would be better off probably with head with stock port sizes but optimised.

You need to look at gearbox ratio/max desired rpm and work back from there is how I would approach it.


Edit: if going turbo just run 30 psi at 1500rpm and bleed it off for 2psi at redline for constant 175 bhp haha

 

IMHO

4/2/1 manifold, smaller rather than bigger ITB's, less aggressive cams, more like rally cams than race cams. Possibly an argument for high compression, I only say high compression as F3 cars are air limited and go for torque over power and have BIG compression ratios and lots of torque, the ABF is long stroke so ideal for torque. With only 175bhp at the wheels there is a good argument here for going 8v, I'd wager it would out drag a 16v with that limit on power - and I'm being 100% serious about that.

Might also be worth looking at a diesel crank and sleeving the bores down to keep it under 2.0ltr, depends how much you want to spend and how competitive you want to be. That's what Spiess did on their early F3 engines (with bespoke products of course).

 

Or ......................build it full race and use the soft cut rev limiter to adjust the power seen at the wheels. ie lower the rev limiter until you are bang on the class maximum.
Jon

 

Diesel crank
On std abf is 2042cc, technically still within the 2 litre bracket ????

 

No restriction on cc though lads..could be 5 litre if I wanted ( although that would be silly and unachievable wouldn't it)
being realistic it could go to 2.1 but is there any value..if so then that's the route, but would it give the torque Vs Power equation I am after.?
are we saying it is the crank mods that will make the torque then?

 

TDi allowed?

 

Just calibrate it to 175bhp or less. You got an aftermarket ECU and you can control the torque curve to under perform if you desired.
A ABF car with itbs, cams and exhaust header = 190ish bhp @7200rpm and 155lbfft@5-5500rpm on the dyno I am used to. I could calibrate the engine map to any shape under the max mapped torque shape if I wanted to.

Really your call.

 

Yes, but don't really fancy a full on conversion due to hassle factor etc..prefere to upgrade what just drops in if possible.

 

It has all them mods and doesn't hit that power on dyno I have to use.....maybe it would on others.
It has omex 600 ecu, but don't want to lower torque curve I want to increase it. it is the proportion of torque against power I am after changing
example on the figures you quote of 190bhp and 155 torque , I would be after modifying to be more 190bhp 190lbfft or preferably more lbfft

does that make sense?

 

I would like 190ftlb also..............without a turbo.........
Jon

 

Are you saying its not possible to increase Torque over Power Jon?

 

No, that's not what I'm saying, 190ftlb is a big number for a 2L. If you have already commissioned the gearbox then you have the ratios you have. That will dictate pretty much the engines power band you need for a given size of tyre. IMHO
Jon