moving peak torque to higher rpm's

[ADAM]

how would one do this? i am peaking out at 3500rpm?

[SlowMo]

Retarding camshaft timing will move your power band higher. How well this works in terms of peak power output depends on whether the rest of your set up is better optimized for lower and higher rpm operation. Another relatively simple option would be to have your turbo clipped. Personally, I'd work with the cam timing first. Another side effect of retarded cam timing would be less tendancy to knock.

[rpr]

How about a free-er flowing exhaust? Or is that not applicable with forced induction, turbo especially?

[SlowMo]

Freer flowing exhaust is always applicable, escpecially with turbos. I just assumed that Adam already has the highest flowing exhaust he can get.

[rpr]

Originally I was thinking of a long tubed header, but of course that's not what he needs!

[Dave]

Adam, any idea what rpm range you'll be using on the track with your new super fancy turbo set-up? Until you get the thing on the track can you really know where you want your torque curve to peak? Are you using voodoo again?

My advice is advance your cam timing as far as the gear will go and then do lots of pulls to redline...LOTS! This way, I will be assured of winning the first event of the year :D

[ADAM]

he he..i have a SOHC..no way to advance cam timing..no timing gears available...

i will be revving motor to 6000rpm..since power really drops off at that level....

here is a dyno of the torque

http://son240sx.hn.org/adam/dynorun2.jpg

[rpr]

I'm no expert at reading dyno plots, but it looks like even though you are dropping after 3500, you still have lots of torque all the way to 6000. It looks like the lowest it hits is 230 between 5000 and 5500.

What happened on the green run, did you do it in reverse? :D

[ADAM]

the green run was my engine in solo 1 before the turbo :)

it was NA..nice smooth power band though on the NA

[rpr]

Nice gains! 95hp and 125ft-lbs. Schawing!

[Dave]

Wow, those are still very linear hp and torque curves you've got even with the turbo. Obviously they're not as flat as your NA set-up, but given the big increase in overall power I'd say your hp and torque curves are just about as flat as you could expect. You've got gobs of hp and torque all the way up to 5,500rpm, where torque begins to drop off a bit. If by shifting at 5.5k rpm (obviously depends on your gear ratios and final drive) you get your revs down in the 3-3.5k rpm range, I'd say your power curves are just about perfect. If shifting this early drops you down to more like 2k rpm, then maybe you should try to move your torque curve up a bit, or change your gear ratios :)

You do have a strange dip in your hp curves just below 4k rpm though. What's that about? Looks like you need to add fuel there. I assume you're running a fully programmable system for fuel and ignition timing?

Sweet looking chart overall. So different than mine! I'll be at the dyno in the next few weeks, so I'll post it once I've got my new numbers.

Cheers,
Dave

[ADAM]

yeah lets see what you little girlie honda motor can do(torque wise anyway)...this is only at 10psi and 11psi ..he he... :)

hmm i thought the power band was not peaky enough? i want it to peak at high rpm...i guess we all want what we can't have...i does make for a fun drive on the street though..with alot of torque available at every rpm level..

dave.. the dip at 4k is the wastegate cracking open...my new electronic boost controller will fix that hopefully....

if you can believe these runs were made with a STOCK ecu...and just a piggy back fuel injector computer...

do you think there would be any benifit to rev it out to the 6800rpm i used to do with NA?

when are you going to do your dyno runs? what kind of torque do you expect to get?

[Dave]

I can't see any reason why you'd want to rev to 6,800rpm. All you're going to do at that rpm level is add stress and heat to your engine, both bad things for a turbo application like yours. Heck, the WRC cars on rev to 6k rpm and those things are pretty quick :) If you can make all that power at low rpm, why would you want to bother with 6,800rpm? You do have 5 gears to choose from, right? :p

I'm hoping for about 210whp and 145wtq when I dyno my car. But hey, peak numbers are only for bragging rights, what I'm really interested in is area under the curve. Having as much usuable power in the rev range my engine will be operating (6.5k to 9.5k) is really the only thing that matters to me. Of course I'm also using the dyno to make sure the engine is running within safe parameters (ie. I'm not leaning it out, risking detonation, and all that jazz) and getting my fuel, ignition and cam timing optimized. After that, I'll let my lap times speak for themselves :)

Bring it!
Dave

[ADAM]

this will be a very interesting season :)

see you sunday

[Brent]

Adam, as I understand it an engine drops off in power at high rpm because it cannot efficiently pass any more air through itself. Therefore to extend your power band you need to open up the restrictions to air flow in your engine. Since you are using forced induction my guess is that your cam would be your biggest restriction. Do they make a turbo cam for your car? I know for my car crane makes turbo cams with increased lift and duration on the intake and increased lift but shorter duration for the exhaust to help the turbo spool faster. Porting and bigger valves would help too.

Also extending your block and using longer rods to increase the rod ratio will give the piston more time at TDC and BDC and allow the engine to breath better will make your engine rev better. Or there is the flip side, shorten the block and rods, be damned with the rod ratio, move the rotating mass closer to the centre of rotation and that will help your engine rev better. There is a good article on this at Turbo magazine's website.

But you were looking for something that wouldn't cost points, right.

Also Leitner and Bush can make an adjustable cam gear out of your stock one.

[Shaman]

If we're calling something girly, well... my motor makes 440rwtq at 2,500 RPM and goes up from there to 502rwtq. With no power adder, and pump gas. Feel free to ask Caius what it feels like to have the car beside you insta-dissapear. No turbo lag there...

And I'm still using a hydraulic valvetrain. There's still another 100rwhp hiding in my setup without a blower if I wanted to give up the Horton's runs.

[ADAM]

lets just remember your displacment :)

we are talking sub 2.5l engines here :)

[ctenche]

Are you two boys going to start it up again? :rolleyes:

Listen, I personally like small cars with high revving small displacement engines. BUT...sit in Steve's car for just a couple of laps and he will make you a believer. Having that amount of torque under your control is unbelieavle.

Now stop all that bickering and just get out to the track damn it. And, make sure to give me a heads up when you guys are going to run the quarter at Shannonville. I'd love to see that.

[ADAM]

if we are going head to head..there is not much chance of beating him in the 1/4... i will bring my NOS to help me a bit..it would still be a great race...

its in the curves that the smaller cars can shine :)

steve...what do you do about traction? i am having a real tire spinning issue...

[Shaman]

Traction? What traction?

Kidding. I've got my rear pinion angle set at 0, and I have my shocks and springs set to relatively soft rates in the rear so that the car squats a bit. Because my car understeers a bit, I try to make it up coming out of corners, though I'm working slowly towards pulling the understeer out of it. I concentrated on the rear of the car... with IRS you have an advantage out of the hole, but one thing I'd look carefully at also is making sure you have as little suspension bind in the rear as you can get, so it will work as well as possible.

And, learn how to squeeze the throttle instead of mashing it. The more power you have, the more you need to do things smoothly.