Dyno'd viper today Not Happy!!!!!!!!!!

[VIPER BAZ UK]

Dyno\'d viper today Not Happy!!!!!!!!!!

Smooth tubes and K/N
SeanRoe side exit exhaust with HF cats 2000 headers
Mopar big valves & springs
Ported & flown heads (not polished)
180 degree stat
Arrow roller rockers and rods



5018rpm
418.4 Bhp Flywheel
367.4 Bhp Wheels
power loss 37.9 Bhp

4353 Rpm
463.6 torque engine

30-50 1.6
50-70 1.4
70-90 1.3
90-110 1.1

Could the dyno be out???
Or did they do it wrong??

 

[99 R/T 10]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

What kind of dyno was used? It makes a difference. Dynojet or a mustang dyno?

 

[VIPER BAZ UK]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

It was a dynoplot (well thts what it says on the paper work) I think its about 100bhp out....

 

[Neil - UK]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

a couple of years Dynojet was the way to go, not sure if it still is ? though not many in the UK

 

[STUGOTS]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

seems as tho you sould have a bit more

 

[Buckeye Viper]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

Yeah, def doesn't seem right....

 

[Gerald Levin]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

I guess the only way to know for sure is to do it again on another dyno. That should tell you if the first dyno was right or not.

 

[BigCarrot]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

You should be good for high 13's with that setup. Wow, those numbers HAVE to be off!

 

[Bill B]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

What was your A/F?

 

[YouWish]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

Yeah. That dyno was definately off or you had a couple of cylinders not working!!! Of course i'm joking.

 

[VIPER BAZ UK]

Re: Dyno\'d viper today Not Happy!!!!!!!!!!

The only other info on the sheet was
Min ambient temp 20Deg C
Max ambient temp 30Deg C
Barometric pressure 998mb

Bill B posted
What was your A/F?

How do you workout A/F

 

[Sean Roe]

Re: Dyno\'d viper today

Did you remove the carpet mat and check your throttle cable adjuster for full throttle? You know how those things loosen up.
We've got a routine we have to go through each time in order to see repeatable results.
Do you have the dyno graphs from before and now?
Are they both SAE corrected, actual, or smoothed the same?
Did you get air / fuel ratio?
There are lots of variables.
The torque sounds close, but the HP is way down. This is generally more indicative of an air flow restriction (in or out) in the upper RPM area. Check for full throttle.

Regards,
Sean

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

Sorry for the size but if i make them smaller you cant see....

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[Bill B]

Re: Dyno\'d viper today

A/F = air fuel ratio. It isn't on your printout. It sounds like it is WAY to rich or, like Sean said some type of restriction. The acceleration sounds like your are making better power.

 

[AviP]

Re: Dyno\'d viper today

Also, why did the test stop at 5066 rpm? Shouldn't it go to red line. It won't gain you any additional hp but a better perspective on your power band.

 

[Sam 01 RT10]

Re: Dyno\'d viper today

Don't know about a Gen 1, but max hp on my dyno graph(looking at it now) is at 5,400rpm. If a Gen 1 is similar, then they let off the gas too soon.

 

[joe117]

Re: Dyno\'d viper today

He'd do better than high 13s.
My 96 300hp LT1 automatic Vette has run a little better than 13.8 and that's just playing for fun at the track.
He's low on hp I agree but he would do better than high 13s with what he's showing now.
I'd say low 13s

 

[ViperJohn]

Re: Dyno\'d viper today

We had a Yellow 94 with smooth tubes and K&N's just pull 384 hp to the wheels this weekend at Heffners. As far as I know most dynos correct for temperature and humidity. It seems you should have had a higher number considering the modifications you have made.

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

Hi All
Thanks for all your input and help..
It has clean filters in it and the throttle bodies were cleaned at rebuild..
How would i get the A/F reading? Do i need software for that?
Also as someone mentioned above if i only have 367Bhp at the wheels how can it go from 30 to 110 in 5.4 seconds?
Bit Peed off at the Mo as i have put about $5500 into this car.....
But saying all that it does seem to pull alot harder (but it has been seven months since i last drove it..
It did have a new TPS should i of Reset the pcm?

 

[RedEnuf93]

Re: Dyno\'d viper today

What gear the pull was made?

I mentioned earlier that my Gen 1 made about 380 on third, but immediately with next pull on 4th 410HP.

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

All done in 4th as you suggested..
Could it be the filters and stock airbox blocking airflow....

 

[Sean Roe]

Re: Dyno\'d viper today

That was not done on a Dynojet brand dyno. Most people here are comparing your numbers to Dynojet numbers.

The different types of dynos show vastly different results, however, all the manufacturers say their way is correct. Your numbers look more like something you'd see on a Mustang or Clayton dyno. We have a Clayton load and Dynojet inertia dyno in our shop. On the Dynojet, a stock Viper (Gen2) will show around 395-405 RWHP. On a Clayton, it will show about 316 RWHP. The best you can do in a situation like yours is to do a before and after dyno test using the same dyno (overlaying the graphs to see the power curve differences after mods).

Now that you posted your graphs, it's easy to see what's going on. Your torque peak is about 400-500 RPM higher than a standard Gen1. A standard Gen1 will make max HP at about 5,100 RPM. Your HP graph was still climbing when they stopped the pull. The pull needs to go up another 500-600 RPM. If it starts to flatten out too early, you're back to the restriction (check full throttle, was carpet mat out, etc).

Regards,
Sean

 

[v96gts]

Re: Dyno\'d viper today

When I dynoed my 96 GTS 2 weeks ago I wasn´t really satisfied too. It made 540 engine hp (corrected) and 450 rwhp at 5800rpm. Loss was about 90 hp.Torque 716Nm at4700 rpm ( sorry-we don´t use ft-lb in Germany).For all the modifications it seems to be very low :heads/valves-cam-headers-exhaust-air intake-roller rockers/everything is changed.But i think the dyno shows pretty low numbers,because the car runs very strong,compared to stock.I can tell more in a few weeks , when the Roe SC (8 psi) is installed and dynoed.

 

[joe117]

Re: Dyno\'d viper today

Why would the drive train loss be a percentage and not an almost fixed number?
I can see the loss going up a little due to more force causing sliding gear surfaces to slide less easily.

I wouldn't think you would simply call out a fixed percentage as drive train loss.

 

[ruckdr]

Re: Dyno\'d viper today

joe117, et. al.,
Here is an excellent article describing drive train losses for both automatic and manual trans., and why it is a percentage. Very much detail.
http://www.superstang.com/horsepower.htm#whyauto

Later,

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

Sean
Unfortunatly i did not get a stock dyno done as head gasgets caused the rebuild.
Think i will take it to another dyno and get them to drive it harder and higher Rpm.Somthing is not right.Is it possible for it to run lean,thought the pcm delt with all that??
Wont be for a while as i have just had 4 wisdom teeth removed.
Would i benefit from a one piece airbox?

 

[ViperRay]

Re: Dyno\'d viper today

ruckdr,
Excellent article.

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

Just ordered some 65mm throttle bodies see if that helps (I hope so) and the software to see what is going on in there...

 

[Guibo]

Re: Dyno\'d viper today

Looks like very low drivetrain loss for a rolling road dyno, when using the corrected figures. That's about 51 hp. For reference, take a look at these Cerbera 4.5 dynos showing ~85 hp drivetrain losses. That's about 25%, which by US dyno standards is unusually high for a RWD car. (Stock Cerbies should be making 420 net hp, BTW.)

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[jp]

Re: Dyno\'d viper today

I would not go the TBO way, that´s waist of money, will probably giv you less bottom end. As Sean says, check the trottle cables, you are probably on 3/4 trottle only. How did you install your camshaft, was it indexed properly?, How did yo adjust the lifters?
There is alot of questions to be answered.
I would say that the best way to get a indication of power compared to other modified Vipers, is to get som 1/4 mile trap speed numbers, they do alway tell the truth.