?'s for those with a 2.93 pulley and an aftermarket boost gauge

[jtfx6552]

I installed my boost gauge today. I thought maximum boost would be more constant. It seems mine peaks in the high 3K low 4K rpm range at 12 psi and drops off steadily as the tach climbs to 10 psi at redline.

Does this fit with what you are finding?

I may try the boost dump mod do see if it makes any difference, although I suspect it is the efficiency (or lack there of) of the blower as it gets oversped that is causing the drop off in boost.

JT

 

[Rick@Amazon]

Originally posted by jtfx6552
I installed my boost gauge today. I thought maximum boost would be more constant. It seems mine peaks in the high 3K low 4K rpm range at 12 psi and drops off steadily as the tach climbs to 10 psi at redline.

Does this fit with what you are finding?

I may try the boost dump mod do see if it makes any difference, although I suspect it is the efficiency (or lack there of) of the blower as it gets oversped that is causing the drop off in boost.

JT

Hey JT, You hit the nail right on the head. It's a matter of efficiency. I talk a little about it in a different post. Something else to remember is when you reach that point of loosing boost you are creating alot of heat. This is another reason why these cars should not be spun over 6500 rpm. Check your dyno graph for ruff spots up top right a the point of loosing boost. It also chould be spark blowout. Try some tr6 ngk plugs if you haven't allready. Gap them at .040 to start. If your graph still looks rough up top go to .035 and that should cure it. Also I don't think it's the bypass valve or you would not just have 10 lbs. If you get a chance give me a call.
Rick

 

[Sonic03]

Boost by-pass mod might work...

 

[jtfx6552]

I just added the boost bypass mod. It makes no difference....

JT

 

[46stang]

finally someone is seeing what i have been seeing! when i dynoed my car stock it made 372rwhp at 6400rpm, after the pulley it made 425rwhp at 5800rpm! My boost guage steadily drops from 5800-6500rpm. it reads 10psi on my stock guage at 6500rpm! I tried regapping my plugs to .40 and it didn't help either! I ordered the bypass mod so i guess that wont fix it:bash:
I think it is either blower efficeincy as stated or belt slippage! I even tried removing my air filter to see if it was restricted but it didn't help! keep me posted if you figure anything out and I'll do the same!
Leon

 

[XtraVenom03]

I think its the belt.

 

[Racer X]

Originally posted by XtraVenom03
I think its the belt.

Thats my thought too! But I am a centrifical blower guy... so I might be wrong.

 

[Hammer]

Originally posted by 46stang
finally someone is seeing what i have been seeing! when i dynoed my car stock it made 372rwhp at 6400rpm, after the pulley it made 425rwhp at 5800rpm! My boost guage steadily drops from 5800-6500rpm. it reads 10psi on my stock guage at 6500rpm! I tried regapping my plugs to .40 and it didn't help either! I ordered the bypass mod so i guess that wont fix it:bash:
I think it is either blower efficeincy as stated or belt slippage! I even tried removing my air filter to see if it was restricted but it didn't help! keep me posted if you figure anything out and I'll do the same!
Leon

I think you guys should pay attention to Rick@Amazon about this problem. He's a highly skilled professional tuner and knows these roots blowers as well as anyone does.

I believe that Rick was saying that spark blowout causes an unstable, erratic power curve up top. But it doesn't make boost taper off. And the abuse valve delete (it is NOT a bypass valve delete) is only needed if your boost drops to absolute ZERO at 5200 RPMs. It WONT help you with this problem!!

If you guys are seeing boost taper off up top, you are DEFINATELY dealing with inlet temperature problems. Apparently with that small pulley the blower is turning too fast...outside of tolerances...and making excessive heat that is causing a power loss.

I would say that the 2.93 pulley is perhaps too small for the Eaton 112 in our cars. Remember: a blower can produce only so many CFM's. If you want more you must go to a bigger blower. I ran into this problem with a ProCharger D-1. I put a really small pulley on it and, even with an intercooler, it lost power. When I switched to a slightly larger pulley it gained power.

Maybe a 3" or 3.2" pulley is optimal for our vehicles.

You guys should DEFINATELY consult with experienced professionals on this issue: Jim@JDM, Chris@Crazy Horse, Rick@Amazon, etc.

 

[mineral03]

Ok guys... we know the 112 blower is gonna be pushin its limits pretty soon... so whos gonna be the first to swap on an AUTOROTOR!!! Supposed to make a big difference on the lightnings, so who's going to make one work on an 03?? I thought about it, but not sure if i want to tear my daily driver apart completley to start fabbing... so... whos it gonna be????
Doesnt look TOO hard... make an adaptor to physically bolt the blower on, make sure the outlet of the blower is lined up with the inlet of the intake, add a bypass valve, and build an intake for the back, to bolt the t-body and related stuff... HOW HARD CAN IT BE??:lol: :lol:

 

[david smilovic]

Thanks for the heads up.Im doing alot of bolt ons and Im using the Denso Irridium VS the TR6 for the 1st time ever.From what I hear the blower is overtaxed and JDM is coming out with the 1400.00 fix,if need be I will install and post,Dave S.

 

[mineral03]

Just emailed whipple,wanna get some more info on the autorotor. I may have to break down and do it...seems everything else has almost been done already!! I dont want to be the ONLY guy without 500rwhp!!!

 

[michigancobra]

How are the Lightning guys running so much boost then?

 

[Fast03Cobra]

I was thinking I would like to increase the boost from 7.5/8 to about 10 psi. How would I go about doing that and would I need a chip?

I dont want to do anything radical just a minor tune.

 

[kino]

Just curious does anybody know if thier will be a autorotor for us 03 guys? I like how the L's pulled down 21psi.

 

[46stang]

XtraVenom03: Does your boost bleed down above 5800rpm?


Fast03Cobra: south florida pullies is coming out with/or all ready has a 3.2 and 3.4 inch pullies. the stock one is 3.65 so one of those should put you right where you want to be!

michigancobra: that's what im saying! how do the L guys run so much boost? maybe because they turn less rpms with the motor??? I don't know! But if someone does please chime in

Leon

 

[michigancobra]

Yea 46stang, they turn less RPM'S, but there also
making 17 lbs. of boost. Something doesnt seem right here?

 

[michigancobra]

Have you guys dyno'd your cars yet? what are your
A/F readings? What kind of chips are you running,
and have they been burned to run the smaller pulley?

 

[SB 03]

I also would like to know, maybe I will just go with a pulley to bring the boost to 10lbs. Will have to see what shakes out here, keep us informed about this boost issue, were all insane, just admit it:lol:

 

[jtfx6552]

Originally posted by michigancobra
Have you guys dyno'd your cars yet? what are your
A/F readings? What kind of chips are you running,
and have they been burned to run the smaller pulley?

For me the answers are:
Yes, Nice, Amazon Racing Diablo, Yes.
Curves here:
http://users.rcn.com/drfunky/

 

[michigancobra]

Well there might be your problem right there.
Everyone I've talked to JDM and SFPH says you dont
want to run your A/F over 12.2/1. The best range is 11.5 to 12.2, looks like your hanging around high 12's to 13. Just my .02