GT/SC Paxton want more HP

[SWEDEMAN]

To Paxton owners or tuners:

I love my Paxton GT/SC, what an incredibly balanced car. I was thinking if I wanted more HP, what are my tuning options? Is there any tuners that have upgraded tunes that are credible and won't ruin the engine?

The Paxton is very quick and controlled, just curious if there may be more HP available.

Thx

[andrewnagle1964]

what is your current rwhp ?

[SWEDEMAN]

Hey Thanks Andrew.

 

It is 465. My whipple was pushing 505 but it was immediate HP and tons of wheel spin. The Paxton comes on great at 27-2800 RPM's and the wheel spin out of the hole is non existent almost, it shoots straight as a string per Shelby blogs!

I wants to push this to about 495-500 if possible

Thx

[mhr1961]

If I am not mistaken Brenspeed offers some Paxton kits/tunes to get you to around 565 flywheel. You may want to call them. If they cant help you, they may be able to point you towards someone who can. Good Luck.

[HARALD KELLEY]

Mine is 424 at rear wheels. Still same tune from when it left Shelby. JeffJ has had some tuning done. Maybe he will chime in on who he used

[TheKurgan]

I would not go any higher on the stock bottom end. However it is very easy to just go to a smaller pulley. I run a 2.62 pulley.

[JeffJ]

If you're already at 465 rwhp, I wouldn't be looking for much more on the stock internals. That is pushing it pretty hard. I'm at 510 rwhp right now but can do much more with the forged aluminator I'm running. I just had a local tuner do mine(Finishline Performance). At this altitude (over 5100 ft), not many canned tuners will have anything that would work for me, so had to go local. I'm pretty much maxed out with what you can do with the 1200 Paxton. If I want any more, I need to get the bigger unit to push more air. I am running a very small pulley to spool it up quite a bit. I'm not sure there will be much more you can do without going to a smaller pulley and then custom tune, but much more and you will be loosing your bottom end pretty quickly. I also have not upgraded the transmission at all other than a converter, so I'm already risking the tranny going with too many passes down the track. But so far so good. Once it goes, I'll upgrade it with stronger clutches and other internals.

[twobjshelbys]

If you're already at 465 rwhp, I wouldn't be looking for much more on the stock internals. That is pushing it pretty hard. I'm at 510 rwhp right now but can do much more with the forged aluminator I'm running.

 

Jeff speaks from experience here (His aluminator replaced a blown engine.).

 

The conventional wisdom was that the 3V 4.6L was good to about 600+/- crank HP. Also note that the HP changes with altitude, so if you set it for 600 at 6000' changes are good it's good for about 700 at sea level and there can be a consequence of that Bottom line is that high altitude home base tunes will tend to be a little conservative.

 

But what I hear the OP asking for is more HP at the low end, and the truth is that the Paxton/Nuvi centrifugal design is essentially a higher RPM blower. If you want more HP at the bottom then the safest way is to replace it with a Whipple/Kenne Bell.

[SAI-Steven]

Hey Thanks Andrew.

 

It is 465. My whipple was pushing 505 but it was immediate HP and tons of wheel spin. The Paxton comes on great at 27-2800 RPM's and the wheel spin out of the hole is non existent almost, it shoots straight as a string per Shelby blogs!

I wants to push this to about 495-500 if possible

Thx

 

That's definitely "possible" but so is the possibility that you'll be looking for a new engine, you'll have to make the decision of risks vs rewards.

 

Yes others have pushed their engines to 500+ hp with no problems (yet) and others have put a rod through their block with 425 hp. I sometimes compare stock engines to people, some people live a hard life and live to be a 100 years old while others seemingly live a somewhat mild life and are dead at 60.

 

If you're looking for more grunt off the line I would suggest changing your gears to 3.73 also if your car is running that Paxton diablo tune with the mafia add-on I would certainly consider ditching that tune for something better but not necessarily more aggressive.

 

I would strongly urge that you don't try to wring out anymore horsepower from your setup. We are talking about a 10 year old engine, yes I know your car has low miles but its still 10 years old, that was never designed nor intended for 500hp. If you really want that additional hp I would suggest you have the internals replaced with forged parts.

 

Steve

[HARALD KELLEY]

 

That's definitely "possible" but so is the possibility that you'll be looking for a new engine, you'll have to make the decision of risks vs rewards.

 

Yes others have pushed their engines to 500+ hp with no problems (yet) and others have put a rod through their block with 425 hp. I sometimes compare stock engines to people, some people live a hard life and live to be a 100 years old while others seemingly live a somewhat mild life and are dead at 60.

 

If you're looking for more grunt off the line I would suggest changing your gears to 3.73 also if your car is running that Paxton diablo tune with the mafia add-on I would certainly consider ditching that tune for something better but not necessarily more aggressive.

 

I would strongly urge that you don't try to wring out anymore horsepower from your setup. We are talking about a 10 year old engine, yes I know your car has low miles but its still 10 years old, that was never designed nor intended for 500hp. If you really want that additional hp I would suggest you have the internals replaced with forged parts.

 

Steve

 

Agree Steve, some day I intend to change the Diablo tune, ok been saying that for some time but just maybe some time I'll get to it. Strongly do agree. The hp is fine however the tune has room for improvement related to shift points, etc.

[andrewnagle1964]

Swedeman

 

I much prefer the Paxton to the Whipple

 

Have a forged aluminator as my block with a stock Paxton pulley

 

3.73 gears, Exedy 500 Mach clutch and the all important brake upgrade !!!!

[SWEDEMAN]

Thank you Andrew, Jeff, JeffJ, twobjshelbys, the kurgan, mhr1961 and SAI Steven. Actually the car is very impressive all the way through, I was just remembering the massive 596 crank hp on my Las Vegas GT/SC whipple, really I couldn't use it, but makes you want it!

I can't in good mind play with the tune, even though I want a bit more. Also I don't run this car hard at all and it is heated and cooled, stays inside all winter until all the pebbles are off the roads. I really want like 485-500RWHP, but not at the risk of blowing my engine or causing it harm. The car now has 1540 +\- miles and is truly an incredible car for a 2007 GT/SC, not too much out there can beat it. I think maybe, 3.73 gears maybe, but leaving it totally stock is probably the best now that I hear all the information.

Thank you all again.

[ITHERTZ66]

Wise choice to leave it be. My Whipple charged Hertz has crazy torque down low and loads of horsepower that I'll rarely be able to use. Last tuning dyno was around 450 RWHP with the standard large pulley. i have no desire for more power. I actually had it re-tuned a bit to make it more predictable on the street and easier to modulate the throttle without spinning the tires. Once these tires are done, I'm putting fatter rubber on this car and likely will install the Brembos I have sitting in a box. With my SCT tune, I can modify all the shift points and other drive-ability factors as I see fit just by letting my tuner know what I'm experiencing and what I want as I put more miles on the car. He can email me a new modified tune to load myself.

Edited February 28, 2017 by ITHERTZ66

[shelbytexan]

You might consider 410's instead of 373's as they are already pretty close to your 355's. I as you know have the 410's with the whipple but you would get them rpm's much quicker with the 410's. I always tell people it felt like i added 50 more hp with 410's. If i had installed the whipple first then i would have just left it alone but this setup works great in 3rd and 4th gear on the whipple. If you want a big difference coming out of the hole then the 410's might be just what you need. Good Luck in whatever direction you go.

[William Rodgers]

I don't understand 4.10's with the whipple, it already doesn't hook up, wouldn't this just make it worse? I'd rather have the length of each gear, but I don't drag race, I never even spin my tires (on purpose). I really only use the power taking on ramps and occasionally on an empty highway I'll gun it to get a quick rush and back down again.

[SAI-Steven]

I don't understand 4.10's with the whipple, it already doesn't hook up, wouldn't this just make it worse? I'd rather have the length of each gear, but I don't drag race, I never even spin my tires (on purpose). I really only use the power taking on ramps and occasionally on an empty highway I'll gun it to get a quick rush and back down again.

Yes 4:10 gears would exacerbate rear wheel tire spin with a screw type supercharger like the whipple & kenne bell superchargers. Paxtons could probably tolerate 4:10's more because of their centrifugal lag before getting into full boost.

 

Remember Ford built the car with 3:31 gears, the Shelby package increased it to 3:55 and the Shelby mod shop gears are pretty much always 3:73 gears. 4:10 gears are best suited for specific applications and are not common.

 

We here at Shelby rarely install 4:10 gears, usually only when the customer insists, and then the customer calls us back complaining that they can't use first gear anymore and that they aren't happy with the gear noise on the highway.

 

Now with that said there will be some owners that are in love with 4:10 gears and are willing to put up with the trade offs. My suggestion is if you don't have previous experience with 4:10 gears be sure to find a friend with 4:10 gears and drive their car to see if you're willing to accept the same trade offs.

 

Steve

[AstroDan]

I would not go any higher on the stock bottom end. However it is very easy to just go to a smaller pulley. I run a 2.62 pulley.

Late poster on this thread, but so true.

[TheKurgan]

Late poster on this thread, but so true.

 

Classic rod through the block there. I've seen it too many times. Why Ford didn't put stronger rods in the motors I don't know. That is really the only weak link.

[shelbytexan]

I did say i installed the 410's before the whipple. 373's are probably best for the whipple but i believe 410's could help the paxton . If i were a few years younger then i might change back to 373's but i know how to respect the 410's and realize it can get away from you quickly especially in 1st and hitting it hard going into 2nd. If you are on the freeway going 60 mph then not hardly anyone can touch you. Just ask my buddy with the 79 camaro with the supercharged 454.He said it's not fast, it's quick.

[slbgtsc]

You can put a set of long tube headers on the car to pick up 20-40 more HP.

[SWEDEMAN]

I was think of Long tubes. I may go that route.

 

The smaller pulley, is that safe? Your running a Paxton 1500, what do you think mIne is the 1200 IC from SAI.

Thx

[andrewnagle1964]

I was think of Long tubes. I may go that route.

The smaller pulley, is that safe? Your running a Paxton 1500, what do you think mIne is the 1200 IC from SAI.

Thx

Love my American Racing LT's

[TheKurgan]

I was think of Long tubes. I may go that route.

 

The smaller pulley, is that safe? Your running a Paxton 1500, what do you think mIne is the 1200 IC from SAI.

Thx

 

The pulley I'm running would not be safe on the stock internals. The paxton/vortech pulleys fit all paxton/vortech superchargers. If you are really wanting more horse power, I'd go ahead and replace the rods/pistons.

[SWEDEMAN]

Thx. Since it is a very fast car anyway, I'm leaving it be. I really think Carroll got it right with the Paxton, straight line out of the hole with very little spinning and comes on strong at 26-2800 RPM's. My Whipple was just the opposite, zero control of of the hole unless you can feather the gas pedal, this is way different.

The Paxton was slated for all GT/SC's, until 50 state emissions was toast. Mine is 50 state legal one of very few.

Thank you all for the replies

[andrewnagle1964]

Thx. Since it is a very fast car anyway, I'm leaving it be. I really think Carroll got it right with the Paxton, straight line out of the hole with very little spinning and comes on strong at 26-2800 RPM's. My Whipple was just the opposite, zero control of of the hole unless you can feather the gas pedal, this is way different.

The Paxton was slated for all GT/SC's, until 50 state emissions was toast. Mine is 50 state legal one of very few.

Thank you all for the replies

Agreed and good decision.

[shelbytexan]

It's easy to turn them into a money pit. I'm a slow learner in thinking if it ain't broke don't fix it. I only suggested 410's so that you would get into that 2600-2800 rpm range quicker but there's not to much out there that will out run your car the way it is. Enjoy the ride.

[39Mustang]

An easy fix if your funds are not an issue??? Swap out the 4.6 to a Coyote and slap on a Whipple and bam HP problem is solved forever with all you ever need

[mhr1961]

An easy fix if your funds are not an issue??? Swap out the 4.6 to a Coyote and slap on a Whipple and bam HP problem is solved forever with all you ever need

The OP stated that he wanted to leave the Paxton in place and that he was looking for tuning options that may provide more Horsepower.

[SWEDEMAN]

It's easy to turn them into a money pit. I'm a slow learner in thinking if it ain't broke don't fix it. I only suggested 410's so that you would get into that 2600-2800 rpm range quicker but there's not to much out there that will out run your car the way it is. Enjoy the ride.

Ken, your right not many can out run them. Also I would not jeopardize the integrity of the original small number Paxton cars for a un original engine just to get a bit more HP. This car is extremely well balanced and is already a very fast car. Ok it's not a monster whipple GT/SC like my last LV Shelby with 600 hp at the crank, at the time the highest horsepower Shelby GT/SC out of Las Vegas. However I could not use it, to much wheel spin like no tomorrow, but fun ...heck ya! I'll leave it as is.

Edited March 28, 2017 by SWEDEMAN

[William Rodgers]

Good call Swede!!! Love that car!!!

 

I agree on the Whipple, I don't drag race at all, but the power is crazy, not useable on most roads. On ramps and passing a car is where it is really fun, but the Paxton just needs a downshift to be just as fun as far as that goes.

 

People wonder how 911's are so fast with less power, it is because they are built with 100% useable power. My 911 S had 385 HP and it was as fast as my 495 RWHP Shelby until you hit higher speeds.