98 cobra vortech boost ?

[98 Saleen Cobra]

Power is power, but the reasoning behind the boost could be that..

last thing I can think of is the blower pulley is smaller than what he thinks.. Regardless of what he bought.

 

[ZeroDCX]

I'm doubtful, as exhaust restrictions should stunt power growth and potential but with an increase in intake restriction/boost.

I'm with you on the smaller sized pulley than stock. Either that or a larger than S-Trim blower/upgraded impeller and over-sized damper.... or combinations of the previously listed.

OP, what's your complete setup? Stock B-Headed 4V motor? 6-rib/8-rib/Cog? Non-Intercooled/Intercooled? A2A or A2W?

What does your tuner make of this?

 

[craigjames46]

98 cobra 4v b head motor stock... stock manifolds with x pipe no cats flow masters car has anderson power pipe and now i put a 3.80 pulley on it on the dyno its still at 12 psi now could they have changed the internals of the super charger i bought it used i dont have a dampiner the pulley i pulled off had 3.60 stamped on it i called vortech and thats the stock pulley size it is for sure a v2 s trim as stated on the tag it is a 6 rib

 

[craigjames46]

stock pulleys on the car

 

[craigjames46]

tuner said change the pulley too a bigger size i did that and its still high 12 psi at 6500 which is better but still too high stock motor non intercooled either im stumped

 

[98 Saleen Cobra]

Pull the serial number off the blower and call up Vortech to run it.. I wonder if they upgraded the impeller to a T-trim or something. Either way the pulley should have dropped boost what you saw before.. Weird.

 

[ZeroDCX]

Pull the serial number off the blower and call up Vortech to run it.. I wonder if they upgraded the impeller to a T-trim or something. Either way the pulley should have dropped boost what you saw before.. Weird.

Before the OP was running the 3.6'' pulley and making 12psi @ 5K RPMs. Now w/ the 3.8'' pulley he's making 12psi @ 6.5k RPMs. So CFM per RPM has come down some, shifting his power curve to the right.

OP that's why in a previous post I mentioned that you should call Vortech w/ the serial number. I'm thinking this unit has been upgraded to at least an SI-Trim (1150cfm). But even those boost numbers sound high for an SI-Trim. You're almost pushing boost number w/ the stock 3.6'' pulley the older Novi2k's would with their stock 3.5'' pulley (15psi @ redline)... and they push 1400 cfm. An S-Trim pushing 1000cfm should be no where near this. Not even the T-Trim @ 1200cfm should be pushing those numbers w/ a stock pulley. It wouldn't surprise me if you actually had a TI-Trim.

 

[98 Saleen Cobra]

I missed the RPM part ahahaha, that makes sense then.

 

[craigjames46]

ill give them a call in the am have them run it again but they told me it was a v2 s trim also says that on the tag I'm about too take it out sell it and buy a new set up at this point ..... no i have another issue wot i get a smell of gas check the injectors no leaks all dry looked at the mat on the hood looks like the shredder valve went off what would cause this ..... this suppose too be a bolt up a go thing turning into a head ache

 

[ZeroDCX]

You could remove the power pipe to drop boost some (~-2psi) and reduce timing to de-tune power output to safe levels. How much timing are you running?

In all actuality, if I were in your position, I would run a wastegated setup (assuming you're air-to-air intercooled). Run the stock 3.6'' pulley and release all boost pressures above 8psi to atmosphere. You would have the best of both worlds, higher centrifugal increased adiabatic efficiency and more torque at lower RPMs (sooner and flatter power/torque curves).

Regarding your fuel issue, are you seeing black smoke at WOT? You could just be running rich. I'm sure your tuner did this to ensure some form of safety too (Cooler combustion temperatures to prevent pre-detonation). Did you try to run the car w/ the FPR vacuum line disconnected and check for leaks? (It can take a while at times). Also are you sure you don't have any exhaust leaks. Remember that you have a catless x-pipe and possibly a rich tune, so there will be some associated unburned fuel smells. Do you have a wideband to monitor A/F ratio? What do your spark plugs look like after a WOT pull? Also post MAF boost leaks will cause the car to run rich as metered air is escaping and not being consumed by the engine, while the ECM is commanding fuel to meet metered MAF demand. Just something else to look out for.

Edit: Just saw your comment concerning the schrader valve. I would replace it. It could be leaking under increased pressures (under boost). Fuel pressure increases w/ boost one-to-one above 0inHg, so a force induced system will see greater fuel pressures than naturally aspirated systems; Highlighting issues previously not seen before.

 

[craigjames46]

i don't think he messed with the timing that much cause the car was already making big numbers at 5000 i can ask him ... plugs are brown color i don't hear any leaks in the exhaust i could put my high flow cats back on if that will help ...i don't see any black smoke at wot ..
mass air meter is all tight so check that .... haven't ran the car with the vacuum line off the regulator too check for a leak didn't know i could do that ill try that now would .... no wide band yet working on that part

 

[craigjames46]

what if i run a front mount ... and what company sells one for a good price

 

[ZeroDCX]

I typed all that stuff and realized you mentioned it looked like the schrader valve was leaking. I would replace the valve for piece of mind.

A wideband is an absolute must when running a force induced setup on a vehicle not originally designed with one by OEM. You can easily discern between running too lean, too rich and stoichiometric. It can also help you diagnose future issues with your car.

I can assume by your previous post you're not running a Air-To-Air or Air-To-Water setup at the moment?

Regarding the front mount there very limited, essentially no pre-built, options for SN95 guys... especially 4V SN95 Cobras. You might get lucky and find a Procharger front mount setup for SN95 Cobras, but these are far and few between. CXRacing makes a bolt on kit for SN95 GTs. It will work, but some piping will need to be changed (GT intake tube location/setup versus Cobra). One way or another, you're going to have to fabricate your own setup.

 

[craigjames46]

had vortech check the numbers and its a stock v2 s trim they havent done anything too it so im stuck on this ..

 

[Boost or Bust]

This is a old thread but how did it end?