Low Mph = Low Power?

[boostmaster]

I have an 85 T Type that has been upgraded with a ta49 turbo, 009's, lunati 200/200, 10" 3000 stall convertor, walbro 308 w/hot wire, 2 1/2 down pipe and hooker cat back system with test pipe and posi, on a rebuilt stock longblock. I went to the track last night and ran a 14.022@96.59, 8.913@78.23 on a 2.147 60ft with 225/60/15 street radials. Despite the low ET's even with just my bolt ons I would think my MPH would be higher. I know it's not an intercooled car but I would think I should be I second quicker. But I know that MPH is power and it seems that I don't have any and all the tuning in the world can't give it to me. Can some one give some imput on what to do next.



PS, all runs were made with 100 octane, 20 psi boost on jl93 octane chip.

 

[blackbuick87]

I dont know a whole lot about hotairs but it looks like you are around 250rwhp (guess)

If its not pig rich and the exhaust isnt plugged or the header isnt cracked I would do a compression test.

 

[boostmaster]

Already did. compression test 140-145psi on all cylinders, O2's in the 810-830 range 0-5*knock, with static fuel pressure@ 42psi.

PS, all variables apply for hot air / intercooled only hot airs may require a little more fuel to suppress knock since it does not have an intercooler.

 

[John Larkin]

Looks like you are dead nuts on stock intercooled TR times and MPH. Now you have to up the ante. Race chip, real race gas, more boost and slicks, plus an EGT and knock gauge. There's a strong chance you can cut a full second and add 10-12 MPH right there. If that's what you want, you should only be about $500 - 700 away with some smart shopping.

 

[FJM568]

Completely stock(turbo, injs) with the exception of a KB 1txb cam, the 87 ecm upgrade, a Jay Carter street chip on about 20# of boost, and a .030 over rebuild, I ran a 14.08 @ 98 with my 85...

I would think that with a TA-49 and 009's, that you could get more power out of your motor than I did with mine...You should be in the low 13s easy with your setup...

posted by boostmaster...
PS, all variables apply for hot air / intercooled only hot airs may require a little more fuel to suppress knock since it does not have an intercooler.

Actually, that statement isn't exactly true...You actually need less fuel because with a hotair, your air charge from the turbo is hotter and less dense, thereby requiring less fuel than an intercooled car...I would try to lower your fuel pressure by a pound or two and make another couple of runs, keeping an eye on your knock retard...Run more octane to suppress detonation...If you find that your mph has gone up by lowering the fuel pressure, than lower it another pound and make another run...repeat this process until you start to slow down again, then increase fuel pressure back to your last fast setting...

 

[boostmaster]

posted by boostmaster...
PS, all variables apply for hot air / intercooled only hot airs may require a little more fuel to suppress knock since it does not have an intercooler.

Quote by Fjm568
Actually, that statement isn't exactly true...You actually need less fuel because with a hotair, your air charge from the turbo is hotter and less dense, thereby requiring less fuel than an intercooled car...I would try to lower your fuel pressure by a pound or two and make another couple of runs, keeping an eye on your knock retard...Run more octane to suppress detonation...If you find that your mph has gone up by lowering the fuel pressure, than lower it another pound and make another run...repeat this process until you start to slow down again, then increase fuel pressure back to your last fast setting...


Fjm568, I thought you needed fuel to make horsepower? I can't understand how decrease in fuel pressure can increase power and trap speed.

 

[FJM568]

If you are too rich, you will slow down too...There is a happy medium there...

The suggested fuel pressure is just that...Suggested...It is a starting point and is not set in stone...That is one variable used when tuning your motor in...

One the other hand, if you lower your fuel pressure from where you are at now and you go even slower(and if you get more knock), than by all means increase the fuel pressure to see if you go faster...But I still think that you are limiting yourself by using 100 octane...But adding more fuel to suppress detonation is the wrong way to do it(unless you are running lean), not to mention you will also probably go slower still...There is no substitute for octane in that case...And to take advantage of the higher octane, you really need to run more timing than that street chip has in it...

 

[boostmaster]

Thats a good point you make about limiting myself with 100 octane but I was running 22-24psi of boost and barely getting any knock. I like the idea of running less timing and more boost. On you second comment even though you make a good point about going faster with lowering your fuel pressure I'm not talking about ET'S I'm talking about power and I don't think lowering fuel pressure will increase power though it will give a more crisper bottom end. thats just my O2'S worth maybe some of the other experts can chime in on this.

 

[striker_29]

I'm a little confused, I guess. At the top of the thread you said all runs were on 20 lbs of boost. In your last post you said 22-24 lbs of boost. I could understand your et and mph at 20 lbs, but at 24 lbs???? That should be approaching the sweet spot of your turbo.

 

[FJM568]

I wasn't specifically meaning ET's, I meant mph...But with traction off the line, more mph usually means faster ETs as well...

If you can lower fuel pressure and get a crisper response at lower rpms, and then lays down at higher rpms, then that generally is a chip programming issue(if the valve springs are known to be good)...You would then need to have your chip re-burned to reflect what you've found and you need to either supply whoever is burning your chips with some type of scantool data so that they can fine tune your combo in...