If you guys will remember a couple of months ago. I posted about fuel pumps and if a Walbro 255 would be enough for my motor because my in line T-Rex was not holding up. Well it turned out to be a Walbro in line which is besides the point. My car would shut down between 4,600 and 5,000 and wouldn't pull any more. I thought it was a fuel problem. I swaped to an in tank 255 to no avail. Long story short. I scanned the motor and sent the scan to TPIS. My MAP was being cut in half along with my IPW and O2 volts. The told me I had a restriction and to find it. I went out to the car and took off the intake boot and the car runs like a raped ape. The engine wanted so much air it was collapsing the plastic/rubber boot and killing the intake flow. I took some sheet metal and lined the inside of the boot and now have no problems. It only took a year to find that problem. Next step is off to the track and some tuning. Hopefully I can put some 11.50s down. Thanks for all your guys help. You led me to find other little things I had wrong with my set up.

------------------
91 Z28 ALL FORGED 383,EAGLE 6" RODS,11.2:1 SRP PISTONS,TOTAL SEAL RINGS,MINI RAM,ACCEL 58mm T-BODY,AFR 210'S
int. exh.
.600 298.3 .600 261.4
COMP HYDRAULLIC ROLLER
236/242@.050 .555/.575, 950-16 SPRINGS 1.900in INSTAL,CRANE GOLD RACE 1.6 ROCKERS,CLOYES ROLLER CHAIN,MILODON OILING SYSTEM,HOOKER SPR COMP 1 3/4 FULL LENGTHS, 3"DUALS,X-PIPE, 4,000 VIGILANTE, 3.73,
BE COOL RAD,VIC jR. WATER PUMP,MARCH ALUM U/D PULLEYS,ACCEL 30lb INJECTORS,MSD DIG-6 AND WIRES,DUI DISTRIB AND COIL,TPIS LEVEL 5 PROM,SFI FLEX PLATE AND BALANCER,ADJUST FUEL PRESS REG,RAM AIR,EIBACK DRAG LAUNCH KIT,LAKEWOOK 70/30 F,50/50 R SHOCKS,NO EMISSIONS STUFF,NO A/C.
G-Tech time 12.20@124 w/200lb passanger.

 

Good info.... got to add it to the list of things to look at when things go bad at higher rpm. Was it an older inlet boot? I'm assuming it was the long stock one from the 3rd Gens???

I would also look to see if there is anything before the boot that was restricting flow.

------------------
Fred
94 Formula A3: 381/TH400/N2O

Advanced Tech Posting Guidelines
Detailed Mod's List
11.513@115.59 on motor; 11.162@127.67, 1.643 60' on a 125-shot. Going with a 275-shot this year

 

Thanks for the follow-up! Like in my own field, correct treatment depends on accurate diagnosis!

Rich Krause

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'95 Z-28 383 with Vortech, nitrous, etc.
"1FASTZ28"

 

It was two different boots actually. One was OG and the other one was brand new. It was also the old third gen design. I feel that the intake is still restrictive because uncapped the MAP sits at 4.66 and capped it is at 4.60. That tells me there is a small restriction. In the stock inlet where the filters are there is only about a half an inch of clearance. Plus those filters are pretty small. I keep seeing this filter box in mags that sits on top of the intake manifold and has a 3in pipe that goes to the T-body. I can't find any info on it though. Any insite?

 

LETHALRACER, I remember reading a 396 buildup that had to do with a 3rd gen airbox and air cleaner assembly. They were quite disappointed to see only 266 RWHP when put on the dyno. They said that the sucking sound of the restrictive air cleaner assembly was audible over the motor. They swapped to a custom CAI and gained an incredible amount of power. I believe it was somthing to the tune of 350 RWHP.

I know someone makes a dual inlet CAI, I am not sure of who it is exactly. If I come across it in the next few minutes I will ammend the post with a link for you.

Amazing, I found one. SLP sells one under part number 21030. The cost is 299.99 though. Quite outrageous if you ask me.

www.SLPonline.com

[This message has been edited by RedIrocZ-28 (edited July 23, 2002).]

[This message has been edited by RedIrocZ-28 (edited July 23, 2002).]

 

Is your MAP in volts, at WOT, max rpm? Just playing with the numbers, that's about a 1.2% loss, so at 500HP, you'd be chasing about 6HP. The filter is always going to provide some pressure loss.

I've never tried my setup without the filter, but it might be interesting...

http://cjcfo.fbody.com/members/injun...s/AirBox03.jpg



[This message has been edited by Injuneer 94FormM6 (edited July 23, 2002).]

 

Red Iroc: I checked the CAI out. Not the one I was thinking about but thanks. I am going to the track this Friday. If taking off the boot gives me 2 to 3 tenths I will probably buy one. With that restriction I was running 13.9@99.

Injuneer: My MAP is in volts not kpw or what ever it is. I figure with my motor at max tune it will go 530hp at the crank. What is that, about 8hp. I will have to take another scan to see what it is exactly now but I am pretty sure it was 4.66mv open and 4.60 closed at WOT at 4,000 and above. You have one big azz filter, both of mine combined aren't half that size. I don't think it will have as much effect but it is worth a try.