GrtWht91

so i changed out my stock tpi intake for the superram, manifold, runners, and plenum, stock heads/cam, just bolts on such as TB, headers, the tricks here and there...the car has 3.07 gears...for some reason the car feels slower, it feels like dead spots all through first and second gear, from a roll it feels stronger but from stop to 1/4 mile it feels terrible, i have a feeling its due to a vacuum leak due to the installtion, any ideas or previous experiences, thanks...

tntcorvette

you proabbly have a vacume leak. Should have got a miniram or single plane intake. The S/R is a royal pain in the *** to install. If I remember correctly, you have to tighten the plenum to runner bolts first, then the runner to base intake manifold last and a few are tricky. Good luck.

GrtWht91

i know this has been discussed before, whats the comparsion of the SR to LT1 intake for the L98, i know the power bands are different, but overall which one is the best? and the superram for sure sucks installation wise

tntcorvette

which one is the best depends on your overall combo. Dont get me wrong, when I had a s/r back in 2000 it was great for the combo I was running. Installation sucked....took about 2 plus hours to do. I'de start the car and spray some carb cleaner around the manifold and see if the rpms rise. Or you can hook up a vacume guage and see if it holds steady or not. Do you remember what pattern used to tighten the plenum to runners, runners to base?

tntcorvette

i'de also double check the vacume lines too before digging into the s/r.

GrtWht91

yeah i plan on doing that first of all, as far as the bolts i really didnt do them in a specific order, for the plenum to runners i started in and worked my way out, some were a pain is the *** and i feel that they didnt set right, thats what im afraid of....im tempted to pull it off and re install it....tsk tsk tsk what a pain, i like the installation of the LT1 intake and feel it would be strong will 3.73's....decisions decisions

MEGALADON

I willing to bet its a vaccum leak.

vader86

There is no best. Each is better suited for a specific type of racing (though you can make each get the same times) or powerband preference (mostly this one).

GrtWht91

your right it is based on application, i knew after i typed that i didnt phrase it correct...i just know something has to be wrong on the SR because the way the car is acting cant be right, just time for diagnostics i guess, good ole can of starting fluid/carb cleaner and listen for the bog...i just dont want to have to pull it off and put it back on...

tequilaboy

I don't have any experience with SD, but after my SR install, my airflow through the MAF went up about 20 gms/sec. I would think this would be enough to lean out the tune if not compensated.

Have you tried increasing the fuel pressure? I would start with an additional 4-5 psi in an attempt to compensate for the increased air.

A custom tune may also be in your future.

Note: If you don't have an AFPR, you can use shims to increase the spring preload. A nickel under the cover on my car resulted in 54 psi (up from 47 psi). You shouldn't need to go that high, so find something thinner than a nickel that will fit under the cover.

It is possible to remove the fuel pressure regulator cover with the SR plenum installed, but it is kind of tricky. You need a security torx bit/socket with removeable bit. I pulled the bit from the socket and used a wrench and the bit only on the tricky lower bolts.

You may only want to do this once so an AFPR may be the best way to go.

GrtWht91

yeah i have a AFPR, and i believe the fuel is fine, but i might try bumping it up an additional 5 psi..

hippy

Starting fluid should give you a good guess as to where a leak is.

Why not, from what I read on this forum a SR installation is a cake walk and well worth the 30 extra ftlbs of torque??


P.S. I pulled my Mini off in 20 minutes back in 2005 when the gray gasket **** didn't seal the ends properly.

Sliding

Check your TB to SR plenum for leaking. When I installed mine, stock bolts that I reused were too long and it felt like everything is tightened but there was vacuum leak between TB and plenum.

rlane5

I used a few short bolts and some nuts a bolt when attaching the plenum to the runners.
I went back and forward last summer changing from LT1 to S/R I like both of them, S/R have better Street manner low end torque (1.7s 60 ft) LT1makes more horsepower (1.9s 60 ft) and MPH and it's harder to tune.It will stumble on the bottom end, and you can actually hear it stumbling while driving at very low RPMs.(the bigger the cam the more you will notices it) You really should tune for both intakes (I have a Accel gen 6 DFI )and rising the fuel pressure help a lot for the S/R. My car ETs better with the S/R but won't MPH as good and the LT1 is the opposite it has better MPH. you really needa higher stall convertor and that opens a another can of worms.

If you don't plan on going to the track that much, I would just work out the bugs in the S/R and enjoy the TORQUE.

Randy

AGENT 86

How was the fit of EGR/Runner gasket ?? Mine would have been a vacuum nightmare if i hadn't checked all gaskets to both mating surfaces.

GrtWht91

yeah i feel the need to go back and check all these areas out, i cant say 100% that it sealed good, so prob wednesday im going to start narrowing it down and spraying it to see if it bogs, and when it does im just gonna have to suck it up and start taking it back off

AGENT 86

To ease installation and get a better clamping force, i studded the inside runner holes. I tapped them to 5/16''(a bit loose due to too big a hole for full thread cutting) and used a back up nut on the runner side.
My runner flanges had a bit of bow, maybe from me powder coating them. The studs allowed me to fully seal them.
Food for thought

tequilaboy

I also had some issues with the sealing surfaces at the runner to base interface.

I ended up building up the runner-side surface with some faststeel epoxy to enlarge the sealing surface in the critical area.

One of the egr slots in the gasket would have been very close to the edge of the runner flange if this was not done. I even had the "good" gaskets, not the known bad ones with the enlarged slot.

Hopefully you checked this out beforehand.

To ease the plenum installation, I chose to stud the plenum and use kep nuts or K-lock from below the runners. If you run a search you should be able to find my previous post with auveco stud part numbers etc.

Here's a pic:




Now a question: why would a vacuum leak affect the performance of an SD car?

The leak would simply raise the manifold pressure slightly, similar to an increased throttle opening. This should be detected as extra load, and the appropriate fuel should be provided to compensate. The MAP sensor shouldn't care if the air came through the throttle or through a leak somewhere else.

If the idle is ok, the leak can't be so big that the IAC can't compensate.

How's your idle rpm?

On a MAF car, or even a carbureted car, a vacuum leak would introduce uncompensated air causing a lean condition. I don't think SD cars are really prone to this since the MAP should pick up the manifold pressure in either case.

88BlackZ-51

man that SR is a pita.

SHINOBI-X

That combo would be great! You pretty much need 3.73's with the LT1 intake to make it work good. 3.45's get er done but a lower gear like those is ideal even with a stock cammed motor.