'98 GTS Ported Heads & Exhaust Dyno Results

[TurboRob]

\'98 GTS Ported Heads & Exhaust Dyno Results

Well, unfortunately, I didn't get an opportunity to do a basline dyno stock. So all I can do is guess at what kind of gains I got.

I'm not sure if these are impressive numbers or not. I will say that I'm pretty sure it could dyno more, but I was pressed for time today. It was also raining (humid), and I drove 20 minutes away to the dyno and dynoed without ever shutting the car off (temp was about 208 at the start of the pull). I was also using the stock airbox with K&N's and the rain baffle in place.

I'm a little concerned as to why the HP started falling off dramatically at about 5600? Stock intake? Stock throttle bodies? Stock computer? Any of those a possible cause? At the exact same time, it started to go rich on the A/F scale. Anyone else have any ideas?

Mods are listed on the dyno page linked below:

http://www.LS1Motorsports.com/viperdyno.asp

Thanks!

 

[Afy]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

490 rwhp and 528 rwtq are great numbers. The HP dropping off after 5600 rpm is quite normal all engines show the same charachteristics..

 

[SUN RA KAT]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Great numbers! Now get some headers, high flow cats, and the Roe Supercharger!

 

[Martin D]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

The numbers are not bad. You can certainly get more out of it with additional bolt on's.

Also, fyi - you can get a combination that will make power beyond 5600. My car pulled over 560 from 5500 to the 6200. It did not drop off until it hit the limiter.

Regards,

 

[TurboRob]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Thanks for the input. I'm thinking about trying a VEC1 and maybe some 70mm TB's, and removing the rain baffle next.

Also, are the headers that big of a gain over the stock '98 manifolds? They appear to be a decent design. If so, I don't think I can see spending $1500-1800(?) on a set of headers. If there really is that much to be had with long tubes, I think I'll build some on my own. Surely there would be a market for a set of $1000 stainless long tubes.

Sound like a logical move?

Thanks again,

 

[genXgts]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Hey Rob your 98 has the first year SS header OEM, 96 and 97 had heavy iron manifolds that are garbage. (I just put your header on my car, dyno next weekend!).

The net on your car going to a high dollar header is nil, I'd venture in the 10-15 range over the current setup, might get some debate there, let's hear it!!!!

Your OEM header supports 800 at the tires on blower apps (DLM), for upper limits!!

take care,

 

[Moundir]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

I'm sorry I would have to disagree with you Ryan. It is much more important to have more air coming throught the headers than exiting through the exaust. jmo from prior experiences with other cars

 

[BigCarrot]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Wow, you got those heads done pretty quickly! Weren't you just asking about that last week? That's some good power!

 

[Martin D]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Yes, you will need to step up to a good aftermarket header setup. That is if you want to maximize your potential. The stock "header" setup will not cut it.

Sorry Ryan, the blower car example does not work the same with a Naturally Aspirated application. I have spoken to Doug in the past and there are specific reasons he goes with or without headers.

Final thought - With your ported heads, you MAY want to take a look at the headers from CDI, or SVSI. (I expect to be bombarded by the Belanger groupies)

Regards,

 

[Tom Welch]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Your numbers are ok but....they should be 20 or so hp more for the mods you have.

Your engine should pull with rockers, exhaust, and good flowing heads, up through 5600 rpm before peaking.

I have several dyno sheets of various model year Vipers with heads/exhaust/rockers that make between 505 and 518 SAE corrected rwhp on a dynojet 248.

If anyone wants to see them, please email instructions on how to place them on this forum.

Thanks,

Tom

 

[genXgts]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

hey honest debate is a good thing, sans the mud slinging of course!

bottom line, a 96 car with 98+ headers and cats has pulled 450 in the past (Cone's car), and with Belangers I haven't seen a car pull beyond say 465ish, with high dollar headers.
hence the multithousand outlay has yet to show over a 15ish gain over 98+ headers from what I have gleaned.

Anyone know/read with the highest numbers on a stock car (smoothies/K&N of course), with full exhaust creeping well into the 450+ range?? I do not personally........

 

[Viperoctane]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Ryan,
Youre correct, but thats for a car without ported heads. He should gain more hp by getting some good aftermarket headers. My car dyno'd 400rwhp and 430rwtq with borla catback and high flow catz. After I installed [******] headers and vec1 I gained 37rwhp and almost 70rwtq. I think headers increase gains from all bolt ons.

 

[matt lankford]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

sup rob, good to see you got out of your cobra, mine is stock again and im looking for a rt/10 my self, how do you like yours?

sry about OT

 

[TurboRob]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Thanks again. This thread is bringing quite a few variance in opinion.
BigCarrot - You are correct, we did get them done pretty quick. I think we could have made more power out of them if we had a set of heads to cut into segments first (we're working on that now). Problem was, we went very conservative on the port work, as to not port through the castings. I'm quite confident there is more power there.

I forgot to mention also, the clutch was leaving a terrible smell both during and after the pull. I noticed today, that when I tried to bang 2ng gear, it slipped pretty noticeably. I guess I'll try re-dynoing it next week with a new clutch, some more computer "learning miles", no rain baffle, and some cool down time.

Tom, when you say I should be making more like 505-518, is that with headers? Or do you have cars making those numbers with stock '98 manifolds?

Lastly, how do my Tq numbers stack up? 529rwtq sounded fairly impressive I thought. Maybe not?

Thanks.

 

[TurboRob]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Hey Matt, how you been? I LOVE my GTS. I would highly recommend it. I haven't actually sold the Cobra yet, but I do have someone who is "supposed" to be buying it. You know how that goes...

Good luck with your Viper hunt.

 

[matt lankford]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

hmm, i saw a post on corral from a hawaiian guy saying he bought it. a stroker i suppose...viper hunting *****, where did you find yours?

 

[genXgts]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

good point Venumish, and nice pick up in your case, did you happen to dyno independantly or was it both headers and VEC1 at the same time? Muddies up the mod for mod gain, but we are all guilty of multi-mods at the same time, myself included.

I pulled 421 box stock last year and will post my new numbers next week, see what happens on 98+ headers and Roe Ovals. Then I'll toss the rear **** and X pipe it out the back and rehit the dyno and put to lay the guessing game of that gain. If I pull near 450 I will be very happy in a stock car with exhaust.......time will tell.

 

[Viperoctane]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Ryan,
When I went to the dyno the first run I had the vec1 set at 0,0 stock settings, I pulled 430rwhp and 479rwtq something around these figures. 421 for a stock car, very very good. Keep us posted on what you dyno, hopefully you'll reach your 450 goal.

 

[Mike Adams]

Re: \'98 GTS Ported Heads & Exhaust Dyno Results

Those numbers are good for what you have. To reap the full benifit you should port match the intake and do a set of headers and a set of Random tech cats. If I remember most of Tom's cars run no cats, which with worth 10 to 15 rwhp. So your numbers are about what I have found with all cars.

Sean's vec1 would definetely be a benifit also