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Advice on what to do to my GT
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Posted by: langod

Hi All -- here's the deal. I took my car up to a dyno day the other day. I was a little dissapointed in the results. I dyno'd my car last year when it was totally stock and got a result of 226hp/275tq. Which seemed pretty reasonable for a stock 5spd GT. Since then I've added a K&N FIPK, Flowmaters 40s and a Diablo Predator "performance" tune.

Now, I know that the Flows probably don't add anything, but the K&N is *supposed* to add 10hp. (I'd expect maybe 5) and I expected the Predator to give me 15 to 20.

When I dynoed it I only got 239hp/282/tq. It also has a SUCKY A/F ratio. (see atached scan of the dyno sheet)

So my question is -- what do I do now?

Here's are some of my thoughts, but feel free to recommend other courses of action. (But no, I'm not going to supercharge it!)
1) Dump the predator tune and just enjoy the car as it is. (and save up for a Terminator!)
2) Sell the predator and get a real custom dyno tune. ($400)
3) Try to manually adjust the Predator and maybe add some stuff like an intake/plenum.

If option 3 -- anyone have any advice on settings?

Anyway -- thanks in advance.....

Posted by: badass98svt

definitely go with step 2. get a custom tune done to correct your a/f. plus you will pick up a few more hp while yer at it.

Posted by: EastCoast5.0

Well if you have the $$ look into a Term lol.

Seriously, she does look lean, a custom tune will definatly help you out. Just a word of advice, don't get cought up in dyno #'s. It'll wreck your wallet and wreck your fun with the car. Put it this way, were you happier with the car before it went on the dyno (forget the A/F)?? If you enjoy driving it thats all the matters.

Posted by: langod

The Terminator is a couple of years away yet -- unless I find a killer deal.
Sure, I'm happy with the car at 239. But my goal was to try to get 250RWHP. I was just expecting a little more out of the mods. The Predator alone should've given me the 13hp I gained past my stock Dyno. (Diablosport claims 15-20.) Plus I was hoping for maybe 4-5hp additional from the K&N. I didn't really expect anything from the Flowmasters.

Just out of curiosity: (Assuming I dumped the Predator and went back to 226rwhp)
-- How much could I reasonably expect out of a custom tune?
-- Do you think an intake and plenum would gain me anything worthwhile?
-- How about an uncatted h-pipe?

Posted by: Mustang5L5

I vote plenum, TB anf off-road H-pipe if you can get away with that

Posted by: badass98svt

langod, a custom tune could possibly net you your 250rwhp goal. if not, it'll be damn close. an O/R h or x wouldn't hurt either, broseph

Posted by: Lances03GT

Why dump the Diablo??It can be tuned with that.For the mod's you have that is not bad number's.A CAI will not give you even 5 hp and the tuner with that few mod's is'nt going to add that much either.

You want over 250 rwhp well here you go..
1-Full exhaust including LT header's.
2-TB/Plenum combo
3-Underdrive pulleys
4-Custom tune

With those you should be around 280 rwhp.Take away the LT's your looking at 250/260 rwhp.

Posted by: Lances03GT

Add stage 2 cam's to the above and your right at 300 rwhp.

Posted by: odie

2003 GT. 247.3 RWHP 291.3 lbs torq with a 70mm accufab T/B and plenum, K&N fipk2, O/R X pipe, magnapac C/B, underdrives and a dyno custome tune. That comes through a automatic trans. Food for thought.

Posted by: langod

Quote:

Originally Posted by odie

2003 GT. 247.3 RWHP 291.3 lbs torq with a 70mm accufab T/B and plenum, K&N fipk2, O/R X pipe, magnapac C/B, underdrives and a dyno custome tune. That comes through a automatic trans. Food for thought.

Yeah, good point. I just wish I could get that extra 1 horsepower to get me into the 240s...

Maybe I'll just do something reasonably cheap like pullies or an x-pipe then.

Posted by: odie

try royal purple engine oil

Posted by: Snov001

Langod there are some things that you aren't considering that may help you out. You are looking for the Diablosport to do everything for you and with so much stock items on your car, it can only do so much. Here is what I learned, some of it the hard way and some was good advice. These motors run best when you can get alot of air to it, fuel to it, and you have to beable to exhaust it. I have long tube headers, and of course dual exhaust. I put on a 75 mm TB and Plenium. I was a pipefitter for 20 years before a injury disabled me. Point being I built a CAI that works like a ram air. I made it out of schedule 80 resin PVC pipe 3" from TB to inlet. I hooked up a monometer up to it and drove it around to see what pressure I was putting on my TB. At times I was at 60" on the water column which converts to a few pounds. I knew I was running really lean but it really ran pretty fast. I replaced the 19lb fuel injectors with 24 lb. Now I hooked up the Diablosport Predator to it and loaded the tune. I have a guy who helps me alot because of my disability he is my best friend plus he owns a 94 Cobra. The differance was unreal. I mean this car is a blast to drive now. I got kinda lucky with the way some things worked out like my homemade ram air. I feel like I am still lean so I had a Diablo rep write me a tune taking into consideration all the air and the 24lb injectors. Right now I have a knock from not enough octane so I am mixing 94 octane with cam 2 fuel. I use 12 gal of gas and 3 gallons of cam2 which is 104. The new tune should take care of the octane problem too. The first tune he wrote me didn't work my car wouldnt even start and the hand held didn't recognize my car. The factory had it running again in 2 minutes. Its all codes. I am expecting the email which will have the new tune today. I can't wait.

Langod I hope I helped you out. These cars are so awesome but take alot of different things to really get the HP and torque out of them. Any questions message me anytime

Steve

Posted by: langod

Snov001
Thanks for the info. I have considered a new throttlebody and plenum. I know that LTs make a big difference, but I can't do 'em myself, and I don't think I want to pay for the installation since they have to basically pull the motor to install.
Right now I'm still thinking pullies, x-pipe and then maybe TB/Plenum. After that, I'm gonna stop until I either get a 30-04 Cobra or decide that the Cobra isn't happening and blow the GT.

Posted by: chemo09

I am sure that this isn't what you want to hear, but you really won't be able to tell the difference of 239 - 250 rwhp. I know that not everyone has a nice budget like I do (to SC), but really think about the fact that you are dumping money into the car for minimal HP gains. Save for the 03 cobra and spare the headaches of blowing a GT. I could write for days about that lol. good luck either way.

Posted by: badass98svt

11 rwhp can definitely be noticed.
sure, he could buy a car that's already super charged, but who can't?
sc'ing a GT is different and not everyone has it. it's nice to be different

Posted by: chemo09

I love having a supercharged gt. the looks you see on faces after they have been spanked is priceless. I will never sell mine, but if i had to do it over I would have bought an 03 cobra. Forged internals, ported and polished, valves, cams, ..... trust me it adds up. 402 rwhp is a blast, but comes with a price. All with no warranty and that's the scary part. It's your money langod and there is no better way to spend it than on speed

. you can't go wrong either way.

Posted by: SMOKE

Good luck with whatever your decision .. there are tons of blown GTs locally. I think the NA guys are the minority.

I know it's tough to decide ... factory blown or personally blown. There's the personal satisfaction of build the car to your specs and comforts or having it already done. I just advise decide before you pour money down the drain that you could diverted to your goal.

Posted by: Snov001

Ya know its a real delemia between keeping your GT or trading to a Cobra and getting the forged internals and having something to build on. I am 47 and I know what I am going to do. I love my GT. Sure there are cars around that are faster and quicker but my GT has that nice big hood scoop, it sounds freakin awesome and its a nice car. I have no intention on selling it. A buddy gave me a really good Idea which I am going to do. Everyone knows you can buy 5.0 parts for about 1/2 the cost of 4.6. I am going to look for a 5.0 foxbody in decent shape, maybey higher milage and build the engine from the bottom up, forged internals the whole deal. I did some pricing and I could really build a kicka-- engine for a price that isn't going to kill me. The Cobra I'd have to buy( I own the GT ) then scrape dollars together buying parts here and there as you have the extra $$ plus hear the wife complain
about spending 400.00 for a throttle body when she needs new curtains in the spare bedroom. Well thats my plan, have one stang that is a nice rider and another one that kicks butt and takes names! Now don't get me wrong it will look good too. The real upside is my first cousin has a service garage so if I needed advice he is a stones throw away. I also have a friend who is a bonifide engine builder. He builds race engines for a living and has the dyno. Whats really cool is there is no rush to get it done!

Posted by: mdevaney

Nos All The Way

Posted by: Noob55

I thought the 99 up gt's had 260 horse? Or is that the cobra?

Posted by: bullitt5177

Quote:

Originally Posted by Noob55

I thought the 99 up gt's had 260 horse? Or is that the cobra?

You are correct, but that's at the flywheel. Typically stock late model SN95 GTs put down around 225-230 horsies at the wheels.