forcefedjunkie

After numerous runs at local tracks and comparing results, going from a Renntech 168mm pulley to an ASP 180mm pulley has made no difference in my 1/4 mile times. I am now running 15 psi of boost vs 12.5 with the 168mm. I averaged 11.60's at 121 before, and am still averaging 11.60's at 121. Must be the additional heat or perhaps tune is pulling timing, I don't know. I should have done a better job datalogging before the swap. I'm now running a 11.8 A/F ratio, same as before. Timing now is in the 10-13 degree area at WOT, not sure what was before. My 1/8 mile trap speeds are in the 94 mph range, about 1.5 mph higher than before. I'm just not gaining as much in the last 1/8 now.

I have a Renntech IC upgrade and headers so that should not be an issue. I'm thinking about getting a TB upgrade but I'll put the 168mm back on first unless the TB will take advantage of the 180mm more. Any thoughts on what may be going on here? Do I need a tune for the addtional boost? The timing seems low to me.

Todd

E55Bullet

I think you really need the larger TB and then a retune and you will be good to go!

prodigymb

+1

Exotic-metal55

Did you compare the density altitude from 168mm best runs and 180mm runs? Like other said, you need tune and more air into engine. You may also not have enough cooling mods and could be pulling a lot of timing after the 8th.. That canbe 20hp loss alone.. Your mph and ET are nice, just follow up with air, tune and check cooling..

Hammer Down

no rocket science here: You need a 82mm TB and reprogram the ECU. I may have missed it but do you have the RT Airbox as well?

Jakpro1

Tune hands down. We've seen this before...no worries.

All kinds of torque limiting voodoo going on with stock car plus tune does not fight the addit boost like it is doing now.

Definitely have heat building up as well. Check those IAT's for sure.

TB adds really nice gains as well. You'll love it.

Mrbig

180 should def add power if you cool car down properly!

forcefedjunkie

Thanks for the feedback. I have a Renntech tune but it was made for the 168mm pulley. I'm hoping the timing tables are skewed very conservatively above 12-13 psi.

What are you guys seeing for ignition advance at WOT? I thought I was closer to 16 deg. at 12.5 psi. Does this sound more reasonable?

IAT's are around 95 F when staged and climb up to 120-125 by the traps.

I still have stock air box.

Todd

bassn_07

Like mentioned above a tune would be needed to fully utilize the bigger pulley.

Your IAT's look great at the end of your pass. Like Exotic mentioned did you take notice to the weather and conditions of both your passes?

Full Throttle

LOL this thread


If you add boost you have to re-tune your car.

Yacht Master

Agree 100%, sounds like the torque limiting flash did not take.
Re tune.

forcefedjunkie

I only run the car when the temps are below 75 deg. All of my runs have been between 65-75 degrees. Low humidy yesterday, probably one of the better days air wise that I've had. Slight tailwind too.

Some tunes I've had in other cars, as well as ones I've written for GM cars, have head room for added boost. MAF tables are interpolated and timing remains constant to a reasonable level. I think this tune must not have much headroom, fueling is obviously correct but other things like timing and torque limits as mentioned may be too conservative.

I've got the winter to think about the next level, probably go with a 82 mm TB and air box, get a tune, and report back with results in the spring. Thanks for your advice.

Todd

skratch77

your car is tunned to run a boost level and has its timing maxed for that level and oct,without knocking,adding more boost will give you better low/mid and then you most def are knocking up top and the car is retarding timing.

complete opposite,you cant add more timing with more boost,it will blow up at some point.Your lucky the car is smart enough to dump fuel and retard timing so prolly no damage was done.

also the e55 has no maf.

you have a very agressive tune right now,I would try some race gas the way it is and do a few pulls,the higher oct will alow your tune to run the same timing and you should pick up a lot of power

stevebez

Higher boost does not automatically = more power...

You got higher IAT's
and higher parasitic losses from the S/C

without a tune its a stalemate, although you dont seem to be having a problem with high IAT's.

Can anyone tell me what the efficiency range of the S/C is ??? then we can resolve this pulley debate once and for all.

Zod

Do you have a tune on your car, aside from TCU?

stevebez

Yep.. Wetterrauer Stage II

See seperate thread of recent dyno.

forcefedjunkie

I was running 100 octane, should have mentioned that.

Todd

Road Racer

How do you measure IATs??

racetested

IAT readings are one of the more common sensors any scan tool can read once plugged into the OBD port.

I use a Innovate LM-2 now but even my cheaper scanguage brand could read IAT's .

hooleyboy

the people who really benefit from the 180 pulleys have a free flowing engine. In turn dropping the boost down to like 13psi or so. Even with shorty headers it may not be enough to free up the flow the 180mm pulley demands.

If you stick with the 180mm pulley.. Your next mod might yield you some crazy gains. Not because the mod itself makes that much power. But because it frees up flow the 180mm pulley needs.

If you want to fit 10lbs of poo in a 5lbs bag. You need the 5lbs bag to think its bigger. Free up the flow and the traffic jam the 180mm pulley's flow rate is creating might dissipate.

I bet your case is a prime example of how long tubes making over 50whp. Or a throttle body gain 40whp.