So my friend bought a roush mustang last year with a stage 1 kenne bell. All the shop receipts came with the car. according to what he got they just swapped the m90 for the kb and put 3:90s in the rear. He measured the pulley and estimated it to be putting out around 8psi (I have not verified this just going off what he said, but on kb's website the stage one shouldnt put out that kind of horsepower until 10psi). So anyway he took it to a reputable tuner just to see what it would put down on a dyno. Well it put down 529.2rwhp @4900rpm and 607.1ft-lbs @4100rpm. And the dynos not off, his dads car went the same day and put down pretty similar numbers as he did on another day on another dyno. What interests me is the power curve. the power just falls off the face of the planet at 5k rpm and the a/f ratio seems a little off. I have the dyno sheet and will post it shortly. But what are your guys thoughts on these numbers? Do the roush mustangs have forged internals? I always thought they were stock gt bottom ends?
crazy power on stock block? (530rwhp/610ftlbs)
quadracer786
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So my friend bought a roush mustang last year with a stage 1 kenne bell. All the shop receipts came with the car. according to what he got they just swapped the m90 for the kb and put 3:90s in the rear. He measured the pulley and estimated it to be putting out around 8psi (I have not verified this just going off what he said, but on kb's website the stage one shouldnt put out that kind of horsepower until 10psi). So anyway he took it to a reputable tuner just to see what it would put down on a dyno. Well it put down 529.2rwhp @4900rpm and 607.1ft-lbs @4100rpm. And the dynos not off, his dads car went the same day and put down pretty similar numbers as he did on another day on another dyno. What interests me is the power curve. the power just falls off the face of the planet at 5k rpm and the a/f ratio seems a little off. I have the dyno sheet and will post it shortly. But what are your guys thoughts on these numbers? Do the roush mustangs have forged internals? I always thought they were stock gt bottom ends?
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if it had the M90, its a stock 3v motor.
if its a P51, it has forged internals, but would come with the Roush TVS SC.
whats the measurement of the pulley?
stage 1 KB is 2.6L?
if its a P51, it has forged internals, but would come with the Roush TVS SC.
whats the measurement of the pulley?
stage 1 KB is 2.6L?
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He bought it with everything done already from a dealer, the previous owner passed away so we cant really call him up and ask. But my friend said it had the m90 on it before the kb. i dont know how he knows that for sure though, i'll have to ask. I do not know the pulley measurement and it is the 2.6l kb
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well those numbers he better be forged....lol, maybe he did that with the m90 just to be super safe... the world may never know
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the numbers falling off:
fuel pump/ injector size?
how much did he buy it for?
bc p51 is much more expensive than a roush with a m90.
got pics of the car?
fuel pump/ injector size?
how much did he buy it for?
bc p51 is much more expensive than a roush with a m90.
got pics of the car?
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Forged or not, something seems off. 530/510 would seem pretty normal. I don't see any way the 4" (8 psi) pulley could make 530 hp much less 610 tq on an otherwise stock motor. The 3.90 gears should, if anything, lower the numbers slightly. As for the power drop off, that's probably the MAF pegging. Mine pegged at 465hp at 6000rpm on the stock motor. And that was at 10psi. Made 465/450..even at 12 psi I only made 500.
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and this shows you why a number from a dyno is pointless. if he wants to know what hp it makes bring it to the track. ET doesn't matter since the mph will show you what kind of hp it really makes.
also check the maf as it is probably pegged. is the a/f ratio going lean at that point? I pegged the kenne bell/lightning MAF at 10 psi and 5000 rpm. also post up the dyno sheet as it would be interesting to see.
also check the maf as it is probably pegged. is the a/f ratio going lean at that point? I pegged the kenne bell/lightning MAF at 10 psi and 5000 rpm. also post up the dyno sheet as it would be interesting to see.
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First off, he is not making 529 RWHP with 8 PSI and a KB supercharger. Not gonna happen. Sorry. Not possible on this engine without turbos.
Secondly, if he WAS making 529 RWHP, his engine is not forged if it came with an M90. M90's NEVER came on a forged motor on an S197 from Roush.
Roush DOES make a "P51 engine", available in the P51 Mustang, the Roush 540RH (Roush Hammer), and the 2010 Roush Stage 3. The P51 engine is an 8.5:1 compression stock-stroke forged power-plant that ONLY comes with the Roush TVS R2300 2.3 liter TVS blower - not the M90.
Even if he did have a forged P51 engine and added a Kenne Bell, he would not make 529 on 8 PSI.
So...the dyno may be a "happy" one, or he may simply be mistaken on his numbers.
As stated above - take it to the strip if you want to see how it is really built.
If he's at 529 on a non-forged engine...he is living on the edge unless his tune is spot-on, and even then, I wouldn't be surprised if a connecting rod or piston ring land gives way.
Secondly, if he WAS making 529 RWHP, his engine is not forged if it came with an M90. M90's NEVER came on a forged motor on an S197 from Roush.
Roush DOES make a "P51 engine", available in the P51 Mustang, the Roush 540RH (Roush Hammer), and the 2010 Roush Stage 3. The P51 engine is an 8.5:1 compression stock-stroke forged power-plant that ONLY comes with the Roush TVS R2300 2.3 liter TVS blower - not the M90.
Even if he did have a forged P51 engine and added a Kenne Bell, he would not make 529 on 8 PSI.
So...the dyno may be a "happy" one, or he may simply be mistaken on his numbers.
As stated above - take it to the strip if you want to see how it is really built.
If he's at 529 on a non-forged engine...he is living on the edge unless his tune is spot-on, and even then, I wouldn't be surprised if a connecting rod or piston ring land gives way.
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The MAF on these cars is good to 1,000 RWHP if you put it in a properly sized housing, IE a large cold air intake.
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who's to say that this is even a Roush Mustang?
try and research it through the former owners and see what was installed.
but if the receipts dont show a built short block, I would assume it is a stock 3V,
bc a built shortblock is something you would definately want to inform the new buyer that is has that.
that is a definate selling point with FI installed.
if i was selling that car, I would put that at the top of my mod list.
try and research it through the former owners and see what was installed.
but if the receipts dont show a built short block, I would assume it is a stock 3V,
bc a built shortblock is something you would definately want to inform the new buyer that is has that.
that is a definate selling point with FI installed.
if i was selling that car, I would put that at the top of my mod list.
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Forged or not, 8 PSI does not make that kind of power on these cars without a turbo.
I have 9 PSI and am making 492 RWHP - that is with Mac long-tubes, high-flow cats, a Mac Prochamber, and Roush extreme exhaust to make things flow more freely. Before my exhaust mods, I needed 11-12 PSI to make the same power.
Maybe, just maybe, if he has cams and ported heads he might pull it off with a few more PSI, but I just don't see 8 PSI making 529. Sorry.
As my sig states, with stock exhaust, I did lay down 512, but that was with 12 PSI and very aggressive timing, and a ton of fuel to keep it VERY rich.
Even if he is forged, a forged engine does not add power - it only makes things stronger. You still need the boost to make the power without displacement.
I have 9 PSI and am making 492 RWHP - that is with Mac long-tubes, high-flow cats, a Mac Prochamber, and Roush extreme exhaust to make things flow more freely. Before my exhaust mods, I needed 11-12 PSI to make the same power.
Maybe, just maybe, if he has cams and ported heads he might pull it off with a few more PSI, but I just don't see 8 PSI making 529. Sorry.
As my sig states, with stock exhaust, I did lay down 512, but that was with 12 PSI and very aggressive timing, and a ton of fuel to keep it VERY rich.
Even if he is forged, a forged engine does not add power - it only makes things stronger. You still need the boost to make the power without displacement.
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Ok im not trying to claim ridiculous numbers and neither is the owner. I dont think its running 8 psi and he's not sure either. he probably measured the pulley wrong. we are just trying to figure out if theres a reason for these numbers. his dads car (new 5.0 with mods) put down very close numbers on this dyno that he did on another dyno. So the dyno is not a particular "happy dyno". we DO NOT KNOW if it has forged internals or not. he would like to find out and if he doesnt he wants to either turn down the boost or go ahead and forge the internals. it is a legitimate roush though i do know that for a fact.
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Numbers are stupid high for only 8 lbs. I dunno if I can believe that I would want to see a dyno sheet...
And if he really does have a standard 3v bottom end I don't see that motor lasting very long. 610 lb/ft?!?!? Hope he has a AAA membership...
And if he really does have a standard 3v bottom end I don't see that motor lasting very long. 610 lb/ft?!?!? Hope he has a AAA membership...
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Look on the door sill for a Roush number. It will be on a white sticker - like this.
If it does not have a sticker, it most likely is a Foush - fake Roush.
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i will but it has the full body kit and all the jack roush signatures, i dont really think its a fake.
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wells here's some of the worst quality pictures you will ever see of a dynograph. the only reason it took so long to post was because i knew my phones quality was terrible and i was trying to find something better to take the picture with. i had no luck with the search 
![Image]()
![Image]()
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Well now i believe it, just dont know what to say lol
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looking at the a/f i'd say he needs to get it tuned. 11.8 is a good a/f and that is showing low 12's to high 13's
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