Dynoed With 2.8, Steg Stage Iv, 460rwhp...

[roach4047]

I got it dyno tuned today at swanson performance, my old numbers were 417rwhp and 462 rwtq with 2.8 pulley, bassanni catted -x, mac 3" catback, straight shot intake with the canned predater tune,(note the low hp number) now the only change has been the steg stage iv w/ t.b and plenum port numbers are 460rwhp and 461 rwtq...im happy with the gains from the port roughly 43rwhp...but I have a boost drop problem at high rpm's, this problem was also existant before the steg port...when you nail the throttle, it shoots to 15psi...by 4500rpm, the boost starts falling off to 10psi @ around 6000rpm...i do have the steeda idler.. and the belt seems to be tight and no signs of belt-dust....is this a possible boost bypass issue??or a boost leak somewhere? im technically 4psi short at the top of the rpm range and i know the tune is good and solid- perfect 11.9 throughout the rpm band w/ no spikes, plugs are ngk tr6,..anyone have a similar issue or ideas???thanks

You said it yourself.... Your springs are to blame for not providing adequate force to hold the intake valve closed during high boost runs eventually overcoming the valve and causing all kinds of havoc to your acceleration, timing, and ets'... You'll only rid this by upgrading your valve train. Untill then it's best you avoid it or have a high price to pay perhaps.

 

[Machinator]

You said it yourself.... Your springs are to blame for not providing adequate force to hold the intake valve closed during high boost runs eventually overcoming the valve and causing all kinds of havoc to your acceleration, timing, and ets'... You'll only rid this by upgrading your valve train. Untill then it's best you avoid it or have a high price to pay perhaps.

This has got to be the least educated post of the day, neither of you know why he is losing boost! 15 psi is not "high" boost for this motor or the valvetrain! He has an eaton, they are very very very very ineficient,the eaton is the reason for the loss in pressure:read: ! Ported or unported or hanging from a tree or with green eggs and ham they suck! I am tired of ignorramous's, stop posting stupid crap guys.

 

[JB]

This has got to be the least educated post of the day, neither of you know why he is losing boost! 15 psi is not "high" boost for this motor or the valvetrain! He has an eaton, they are very very very very ineficient,the eaton is the reason for the loss in pressure:read: ! Ported or unported or hanging from a tree or with green eggs and ham they suck! I am tired of ignorramous's, stop posting stupid crap guys.

c'mon, be nice...

we can't all be as intelligent as you! :bored:

 

[dynobobstieg]

Ok ... I have talked to SEVERAL WELL KNOWN tuners and they all say "porting is very inconsistent" Enough said for me.

I am getting a twin screw soon.

When coming out with a statement such as this, perhaps you should share with us a little more factual information.

 

[dougwg]

MOST tuners don't know crap.

MOST tuners have a god complex.

MOST tuners know just enough to be dangerous.

That being said... there are SOME tuners out there that warrant respect and truly understand modding cars and everything that goes along with it.

 

[IMPORTSMOKER]

I've got an idea on how to standardize the setting of the Boost-By-Pass Valve. Let me run this past you and see what you think.

With the car OFF remove the Vaccuum Line on the Top of the Boost-By-Pass Valve that faces somewhat forward and towards the Drivers Side Fender.

Loosen the 2 bolts that hold the Boost-By-Pass Valve to the Supercharger

Attach a piece of Tubing from a Hand Vaccum Pump (AutoZone) to the open port on the Boost-By-Pass Valve.

Apply a small amount of Vaccum to the Boost-By-Pass Valve, this will retract the arm a certain measured amount. (I used 2.5 in.HG on my test)

Adjust the height of the Boost-By-Pass Valve so the Lever is just resting on the Stop. Do not apply any additional downward force on the Boost-By-Pass Valve when tightening it.

Tighten the 2 Bolts that hold the Boost-By-Pass Valve to the Supercharger.

Remove the Hose that goes to the Boost-By-Pass Valve from the Hand Vaccum Pump. This will release the vaccum on the Boost-By-Pass Valve and apply that certain measured amount of downward force on the Lever.

Re-Install the Vaccuum Line on the Boost-By-Pass Valve.

The biggest question is how many in.HG of Vaccuum to apply to the Boost-By-Pass Valve to Calibrate it and obtain the least amount of drop off in Boost.

Thanks for the good idea, i tryed "pressing 1/8" down" put that was so inacurate...so on friday ill get a hand vacuum and try that...im also getting a gaterback 73.5" belt on there with the tensioner notched...so ill let you know how it goes...as far the amount of applied vacuum....what would be the optimal amount of hg vacuum to apply?? 2-5 inches hg...

 

[moridin2004]

He has an eaton, they are very very very very ineficient,the eaton is the reason for the loss in pressure:read: ! Ported or unported or hanging from a tree or with green eggs and ham they suck! I am tired of ignorramous's, stop posting stupid crap guys.

The boost drop off for the guy's car is not normal. Mine holds ~14-15psi all the way to about 5500RPM and then it drops to about ~13-14psi by 6500RPM. For someone that doesn't want to spend $3000 on a Whipple or more for a KB, plus injectors, then the ported Eaton is the way to go. With the stage 1 port, my family's car made almost 499RWHP SAE with just a 2.8" upper on a Dynojet, with 91 octane in 95 degree L.A. heat. With a Gord's Ford heat exchanger (no fans), my IAT2's are well within reasonable levels (no higher than 135 degrees) after several runs.

We all know the Eaton isn't as good a blower as the Whipple or new KB designs. That's a moot point as far as I'm concerned, because what's going on here with an almost 5psi boost loss is not normal. So, in all honesty, who cares if the Eaton isn't as good as the Whipple or KB? That's not the problem at hand here.

 

[BLK03SVT10TH]

Thanks for the good idea, i tryed "pressing 1/8" down" put that was so inacurate...so on friday ill get a hand vacuum and try that...im also getting a gaterback 73.5" belt on there with the tensioner notched...so ill let you know how it goes...as far the amount of applied vacuum....what would be the optimal amount of hg vacuum to apply?? 2-5 inches hg...

JB suggested 5 in.HG so I re-calibrated mine with that setting an it appears to work great. Thanks JB

 

[JB]

JB suggested 5 in.HG so I re-calibrated mine with that setting an it appears to work great. Thanks JB

you're welcome!

for those wondering about their 'low power', I don't believe it is physically possible for it to get so far out of adjustment that it won't close all the way and cause boost loss.....I may be wrong about this and I'm sure Dyno Bob or someone will let us know if that's the case

you CAN get it to the point where boost comes on too early and that's not good

the bypass is there to protect the blower from excessive heat when idling and at low load...it also gives us our great gas mileage when we are able to stay out of boost

that's not to say that there couldn't be a problem with the internal workings of the actuator....as an example, the bellows inside could get damaged by gasoline in vacuum lines caused by a blown FRPS
.

 

[99SVTcobraVERT]

mine makes 13.9 peak and falls off to 10.9 by redline and ive seen and heard this is normal amount of drop off because of the heaton, but that my boost levels are def low for the mods

 

[danny03cobra]

i have a stage 3 port 2.76/2# and wot is about 14.5psi them drops to12 is that normal? i am in CA. i think that matters

 

[IMPORTSMOKER]

i have a stage 3 port 2.76/2# and wot is about 14.5psi them drops to12 is that normal? i am in CA. i think that matters

i think your having a similar problem as i am...but you should be making about 16-17psi....im gonna re-dyno on sat. after new belt, notched tensioner, recalled bypass valve, different dyno shop, and swapping front tires for rears...so well see...

 

[danny03cobra]

i thought the boost should be around 15psi? how much boost are you making?

 

[IMPORTSMOKER]

your combo should be around 16psi - with that 2#lower...im hitting 14-15psi befor the DROP...

 

[C55AMG]

i would keep tires the same and use the same dyno. Only then will you know if you have truely gain HP from the engine mods or not... You may gain like 10 hp or whatever but then again you know if it was the tires,belt, boost valve or different dyno which helped you. You should use dynos to measure gains over previous mods not to see which one get you higher numbers.

 

[IMPORTSMOKER]

i would keep tires the same and use the same dyno. Only then will you know if you have truely gain HP from the engine mods or not... You may gain like 10 hp or whatever but then again you know if it was the tires,belt, boost valve or different dyno which helped you. You should use dynos to measure gains over previous mods not to see which one get you higher numbers.

I deff. agree with your response...however, where I dyno tuned...the tuner told me A. I may be losing h.p. through my nitto drag radials on the dyno and B. he quotes " my dyno tends to produce lower numbers than other dynoes"...so ill go ahead and make a few mods and get a good final number posted soon.......

 

[Chonger]

you're welcome!

for those wondering about their 'low power', I don't believe it is physically possible for it to get so far out of adjustment that it won't close all the way and cause boost loss.....I may be wrong about this and I'm sure Dyno Bob or someone will let us know if that's the case

you CAN get it to the point where boost comes on too early and that's not good
the bypass is there to protect the blower from excessive heat when idling and at low load...it also gives us our great gas mileage when we are able to stay out of boost

that's not to say that there couldn't be a problem with the internal workings of the actuator....as an example, the bellows inside could get damaged by gasoline in vacuum lines caused by a blown FRPS
.

Hey,

When is boost too early? At what point is it bad? I have the lever on the boost by-pass actuator just resting on the stop. When I accelerate normally I can see a VERY VERY SLIGHT wiggle on the boost gage. The needle just budges a hair maybe 1/2 a MM at initial acceleration and then goes right back. It does not move during regular crusing. It holds boost pretty steady this way.

 

[99SVTcobraVERT]

man i am so damned confused with this whole thread. no one has really answered this question: can the boost bypass effect total psi? because my boost level is def low at 13.9 max and then drops off to 10.9.

 

[dynobobstieg]

The process begins by welding, machining and then hand crafting the finished product to exact specification with the use of templates and micrometer. With much testing it became apparent that the balance of air flow from the low to high pressure side of the blower is critical. When this is done correctly peak torque is increased along with incredible horsepower gains. If boost falls off more than ½ pound at redline, you need a tighter belt, generally a 1/2 inch will do it. Notch the tensioner for more tilt and easier belt install.
The Stiegemeier Stage IV ported blower only flows 1452 cfm this is 502 over stock Cobra Eaton that flows 950 cfm. That is an increased efficiency of 55% over stock.
A stock Throttle Body and Plenum flow 878 cfm, after welding, porting and polishing the cfm is increased to 991 cfm.
This gives the Stiegemeier ported Cobra blower is the most efficient running 15.75 lbs boost, which equates to 18,550 rpm rotor speed at redline, it is tempting to run more boost but what happens is air cavitation and an increase in blower temps which equates to more low end torque but less horsepower.
A Stiegemeier blower combo reduces IAT2s 23 degrees across the board.
A 2.80 upper pulley only can make 14 lbs boost and 500 rwhp 480 rwtq. Add 2 # lower and you can make 15.75 lbs boost and equal hp and tq 515/515.

 

[dynobobstieg]

I had a ported eaton ok! I can also drive with the very best and I am tired of bench racing. I race anyone, all I ask is that we take it to a track because I like to post a time slip after laying the smackdown on somebody. If people believe in the ported eaton thing so much why arent there a plethura of 9 sec ported/ sprayed heatons? The answer is that it just doesnt displace enough. I am not a fan of kb but I am probably about to by a kb 2.8 because they are producing tracktimes that even I cant deny. The whole reason behind this is the massive amount of air they are able to move.

Who ported your Eaton? I can not find your name in my computer files.
Thanks.