Why would my Viper LOSE 80-110 Horsepower coming from Florida to Ohio?

[SUN RA KAT]

I took my Viper to 2 seperate DynoJet facilities to verify the power, torque, and air/fuel ratio using as close as possible the same proceedure that was used in Florida. Other than putting in a new battery and adding 5.5 quarts of coolant/distilled water to my radiator to correct problems with my Viper as delivered to me 2-1-07, only 93 octane gasoline was added. My Viper uses an AEM-EMS.

Larry Macedo in Florida got 739 rwHP and 822 rwTorque maximum numbers 1/16 & 17/07.

Steve Colletti in Ohio got 629 rwHP and 648 rwTorque maximum numbers 3/2/07.

Jeff Wightman in Ohio got 659 rwHP and 733 rwTorque maximum numbers 3/3/07.

Why would there be such a huge difference? Colleti's dyno got 30 MORE rwHP than Larry Macedo's dyno before Larry worked on my Viper (11/14/05 - 2/1/07). Wightman's dyno run was the first time I took my Viper to his shop.

 

[SUN RA KAT]

Here's the graphs that I couldn't post with my above post -

 

[plumcrazy]

did they do any tuning that day ?

 

[SUN RA KAT]

did they do any tuning that day ?

No tuning was done by either dyno facility. Both used the tune that Larry had put in it as it was delivered to me.

I am going to be getting a laptop computer so I can download Larry's tuning program and save it. After that, I will have the car further inspected and a tune put in it so I can at least drive it with a much more correct air/fuel ratio.

 

[plumcrazy]

that A/F looks perfect to me but im no expert by any means.

the weather and conditions are going to make a difference in the numbers

 

[SUN RA KAT]

that A/F looks perfect to me but im no expert by any means.

the weather and conditions are going to make a difference in the numbers

Between 80 and 110 horsepower less in cooler weather? (My dyno graphs were using Larry's SAE smoothing curve and were also SAE corrected.)

The A/F on Larry's dyno graph does look perfect, but the A/F on the 2 different dyno went off the scale below 10:1 = excessively rich.

My car has almost continuous backfiring upon deacceleration and the inside of the tail pipes are deep black heavy soot.

My gas mileage with light throttle (before the dyno runs) was 8 MPG.

 

[KenH]

The cool weather should be factored out with the SAE correction. If it had an affect, it should generally be on the more horsepower side unless the AEM has a deficiency with compensating for intake air temperature changes. I am not familiar with the AEM enough to know how it handles temp changes. It is well established that the VEC2 does have this problem, though in it's case, it runs the engine too rich at higher temperatures.

The A/F is definitely running richer than the original graph. I would expect something in the 10-11A/F range to create more soot on your exhaust pipes and popping, but the effect on decreasing HP should be fairly modest I would think - maybe 20HP?

Are you running water/methanol injection and if so, has this mix been changed from the original tune?

 

[SUN RA KAT]

Everything in the tune is exactly the way Larry had it.

The AEM is new to me, too. Larry finally did send the AEM software disc and I got it yesterday.

 

[mntngts99]

You should post this on the dark-side, you might get more replies

 

[kwkshift]

Does the car feel like it's down 100 hp? That much power should be easily missed. If it feels basically the same, it could be just that different dyno's were used on different days. Make sure they are both set for "SAE" correction.

 

[SUN RA KAT]

Does the car feel like it's down 100 hp? That much power should be easily missed. If it feels basically the same, it could be just that different dyno's were used on different days. Make sure they are both set for "SAE" correction.

I was told by many people to have my Viper dyno tested as soon as possible after I get it back and this was the first time Ohio's roads were not too snowy and icey to drive it. I also had to add 5.5 quarts of coolant/distilled water to my 12.8 quart cooling system first. (I found no evidence of a leak - it looks like someone forgot to burp the cooling system and fill it completely up.)

I've been without my Viper since November 13, 2005 and having it run right. It was at Larry Macedo's all that time except for July 1, 2006 - September 6, 2006 when I had it, and then back to Larry for a second chance at getting the tuning right until he delivered it back to me on February 1, 2007. The car ran so bad when I had it back, I can't really tell what kind of power it was making. It did run 11.9 ET with a claimed 720 rwHP on August 5, 2006, but I've done better ET's with my low 600 rwHP before all the Macedo mods. The roads in Ohio had a lot of salt on them when I've driven it since it has come back, so it's only been light throttle and low speeds, except for the dyno. I went to 2 different shops that uses the DynoJet, since that is what Larry used. I tried to have everything be the same as what Larry used - SAE correction, SAE smoothing curve, etc. to verify Larry's claimed rear wheel horsepower and torque and air/fuel ratio.

Larry has said his dyno gets about 20-30 HP less than other dynos, and that is probably true as he measured my Viper at 585 rwHP shortly after he first got it in November 2005. The Colletti dyno measured my car at 595 rear wheel horsepower before I went from the 5 pound pulley to the 6.5 pound pulley and water/methanol injection - I figure I was at 620 rwHP with that set up using Colletti's dyno.

The small differences in the Ohio dynos are small, but the difference between what Larry's dyno shows and the 2 Ohio dynos are huge. That's why I'm asking the question. I asked Larry the same question and he hasn't gotten back with me about it and that is why it's being asked here.

 

[SUN RA KAT]

You should post this on the dark-side, you might get more replies

I'm looking for answers and not personal attacks, that's why this isn't at the dark-side.

 

[Supercharged Vipermad]

I'm looking for answers and not personal attacks, that's why this isn't at the dark-side.

<yoda>
The protection of the windbreaker is strong here.
</yoda>

 

[valentine_viper]

You're way down on power, the car is running poorly and the coolant level has mysteriously dropped with no signs of a leak... This sounds like a blown head gasket or maybe a cracked head. Either of these problems would allow coolant to escape into the exhast system where it is boiled off and you never realize it. It would also explain the power loss and poorly running motor.

 

[Mr Hemi Head]

I agree with plum, that A/F graph looks fine. There is a rich spot near 4K rpms on 1 run but the rest of the curve is OK. I wish my A/F was that flat.

It would interesting to compare the dyno A/F with street runs, when you get the laptop.

 

[Jerome Sparich]

Maybe I am not looking at the a/f graph correctly, but it looks rich to me.

Black pipes just confirm that.

 

[SUN RA KAT]

63 degrees @ 41% humidity on short drive tonight.

Car backfires while idling sitting still. Also died again in traffic. Exhaust smells real gasoliney when pulled into garage for the night.

I'll recheck coolant levels tomorrow when it is cooled off. I'll also check the spark plugs.

Coolant temperature seems high - 190 degrees - with an 180 degree thermostat.

I had a 180 degree thermostat before that Larry replaced with a new 180 degree one and my car rarely would get over 180 degrees unless I was driving it very slow - 25 MPH in a 25 MPH zone.

I hope this extra info can help you diagnose cause of the problem. I plan on getting compression testing done and a few more tests people have suggested ASAP.

 

[Russ M]

Can you start with what the car has done to it?

My first guess would be that you are missing boost, but I am not sure if your car even has boost in any way.

 

[JohnnyBravo]

The air/fuel looks pretty good to me. It appears to be about 11-11.5:1 pretty much across the board until the big end, when it dips close to 10:1. But rich is safe. And on a boosted car on pump gas, there's nothing wrong with running a tad rich. And depending on how the car is tuned, rich might not mean too much fuel. It might mean too much water/methanol.

Fuel = power. So as a general rule, if a car is lean, add fuel. But if the car is rich, take out water/****. But at first glance, the air/fuel shouldn't be an issue. Even if you leaned it out from 11.5 to 12.0:1, that isn't 100 rwhp.

The coolant will have nothing to do with HP. If you're not finding coolant in your oil, it's not a head gasket. It's just a function of not getting enough coolant back in the system after the motor build. I had the same issue when I did my Roe blower and changed the thermostat. I thought I filled that sucker completely full, but after about 10 minutes of idling, the temp gauge went up pretty fast and I found that I had to "burp the system" and add quite a bit more coolant. I don't think that's a problem or a reason for lack of HP.

Did you ditch your catalytic converters? If so, that will likely explain the gas smell when you pull in the garage and the "backfiring". Without catalytic converters, you won't burn off the extra fuel that's going through the exhaust. So when the raw, unspent fuel hits the hot exhaust, it "pops". Again, nothing to be alarmed about.

All that being said, I have absolutely no idea why your car is so low on power. My 98 GTS with headers, no cats, air filters, rockers and 10 psi made 630/675. That's on a bone stock long block with factory pistons, rods, heads and cam.

I'd get a compression and leakdown test performed just to make sure you don't have any issues. The dyno doesn't seem to be showing any "miss", so I would assume your plugs are not the culprit. But check them anyways.

I was really looking forward to this issue being resolved once and for all. Unfortunately, it appears that there is still something awry with the car.

 

[SUN RA KAT]

I pulled a sparkplug to see how they looked and it was the same reach as the original spark plugs. I heard that the Jeff Morys Striker cylinder heads used hard to find extended reach spark plugs. I called Jeff Morys and found out Larry Macedo had put the wrong spark plugs in my car which is why he couldn't get it tuned right with the VEC2 and has my car not running right after having it back for 5 months to get it to run right. I pulled some more sparkplugs and they were all the wrong kind of sparkplugs!

Larry put in Autolite 3922 sparkplugs and the Striker heads require NGK LFR 7AIX sparkplugs.

It also looks like Larry tuned my car with the catalytic converters not on it on January 16 & 17, 2007 to get his impressive dyno numbers and then he finally put my catalytic converters on after that but never tuned my car with them on!

 

[Russ M]

Spark plugs may cause you to loose power but not that much power, unless they were extreemly wrong plugs. The 3922 is not a bad plug and is a bit colder than what your heads require, but only about 1 heat range colder.

Catalytics will not cause you to loose 100rwhp either, maybe 10-15 if they are poor flowing.

What does this car have done to it? Is it an NA setup with stryker heads? Or is it super charged on top of that?

 

[SUN RA KAT]

Spark plugs may cause you to loose power but not that much power, unless they were extreemly wrong plugs. The 3922 is not a bad plug and is a bit colder than what your heads require, but only about 1 heat range colder.

Catalytics will not cause you to loose 100rwhp either, maybe 10-15 if they are poor flowing.

What does this car have done to it? Is it an NA setup with stryker heads? Or is it super charged on top of that?

The Autolite 3922 does not have enough reach to have the spark be in the combustion chamber! Yes, they are extremely wrong plugs!

I already had the Roe Supercharger, VEC2, Belanger Headers, Random Tech Metal Substrate Catalytic Converters, 3" Corsa Cat Back, 70 mm throttle bodies, S&B air filters, Smooth Tubes, Roe water methanol injection system, and a lot more that was replaced with new stuff.

I'll scan and post most of what was done to my car. Larry has not yet sent me the requested several times list of what he did on it for the 5 months he had it for a second chance to make things right, so the list just has what was listed as being done 6-26-06 when I made the final payment to Larry totally $28,000.

 

[Russ M]

Ok now we are getting somewhere.

I would suggest checking your serpentine belt, they are a very common wear item on superchargers. This is most likely your problem for a few simple reasons.

a) Your power loss is in a big way, either you are missing a cylinder or two, or you are missing boost.

b) Your power curve, while it is lower than before it is still fairly smooth and is not showing signs of lack of spark or detonation.

Your spark plugs are not your problem, they may cause you to have a bit less power but a shorter reach plug will not cause the type of power loss you are experiencing. For example on a fairly stock viper you will loose about 5 hp from a short reach, 1 heat range colder plug.

Do you have a boost guage? Or better yet have you done any datalogs with the AEM in the past to see what boost your car was making? If not to both then hook up a lap top and go for a drive, see if you are making the boost you should be.

PS. If I was your tuner the water/**** would be hooked up to some sort of safety switch with the AEM unit. Meaning if it didnt work, the car would fall into some sort of safe mode with the timing very retarted, and the fuel curve very richened up. Perhaps that is just what your tuner did.

 

[JohnnyBravo]

But if the plugs that are in the car now are the same ones that were in the car when Larry dyno'd the car, that still doesn't explain the drop in power.

If Larry dyno'd the car as it sits right now, and simply pulled the car off the dyno and delivered it straight to your door, without changing the plugs, the exhaust, the tune, etc., then there is no reason why the car shouldn't dyno the same numbers at your dyno as his. My car dyno'd within about 10 hp of each other on 3 different days on 3 different dyno's (up to 300 miles apart) over the course of almost a year. It never changes.

If the car was dyno'd with no cats and correct plugs, and then he put the cats back on and put the wrong plugs in right before delivery, that MIGHT explain some of the power loss, but I still don't think it's 100 RWHP worth.

I'd get the compression test and leakdown test done. You're obviously making good boost (based on the Precision Auto Sports dyno sheet), so that's not the culprit.

 

[SUN RA KAT]

Is it possible that Larry's dyno test numbers on my Viper are the result of skulldruggery? I'd hate to accuse anyone of cheating, but who takes their catalytic converters on and off to run at the track or on a dyno?

 

[InjectTheVenom]

Let's not make comments without any knowledge of fact....

 

[SUN RA KAT]

Let's not make comments without any knowledge of fact....

Just an inquiry...nothing more.

 

[Russ M]

Sun Ra Kat,

The mods you listed are the only ones you have?

How much boost is the blower pushing?

Stock heads? You mentioned something about Stryker heads, do you have them on your car?

If we know what the major power mods on your car are, then perhaps we can start figuring out if 600+ or 700+ rwhp is your legitamate number.

 

[SUN RA KAT]

Sun Ra Kat,

The mods you listed are the only ones you have?

How much boost is the blower pushing?

Stock heads? You mentioned something about Stryker heads, do you have them on your car?

If we know what the major power mods on your car are, then perhaps we can start figuring out if 600+ or 700+ rwhp is your legitamate number.

The other mods are 2" seat lowering kit and related custom mods so I can fit in it with a racing helmet - I'm 6' 5" tall.

Boost measured in Ohio is 13+ pounds, almost 14 pounds. Seems very reasonable using the David Weaver Pulley. Larry took great effort in making sure the serpentine belt had no slippage.

I have the street version of the Striker heads with Jesel Roller Rockers.

Larry first promised that he would deliver "at least the high 700's and maybe even the low to mid 800's in power". He delivered the car to me July 1, 2006 with an extremely bad tune and a claimed 721 rear wheel horsepower. It did run good under acelleration, but horrible at a constant street driving RPM. In mid July I found out from Sean Roe that the low 700's was the maximum the Roe Supercharger can flow. Larry changed his promise of power to the "mid-700's". This may be possible with special port matching and adjustments to the supercharger case which Larry did. Larry told me that even with the bad tune I would have no problem running it at the dragstrip, so I did run it at the ViperNationals in Columbus, Ohio on August 5, 2006. The first 2 runs it blew the fuse to the PCM. My Viper Tech was at the track and he and a mutual friend worked on it and it made 3 more runs without blowing anymore fuses. I did two runs of 11.9X ET @ 123 & 127 MPH. The track was in poor shape and that was the first time (and last) I did any drag racing in 2006.

Larry did get the mid-700's in power using 100 octane race gas and no catalytic converters. I drive to the track, on the track, and home from the track (no trailer), so I have my Random Tech Metal Substrate cats on all the time. I run 93 octane normally, but could use 100 octane unleaded gas if I wanted to.

 

[Earl_H]

At this point, I think you are going to have to bite the bullet and take your car to another tuner. There will be good and bad in this...the new tuner will say that M2 did everything wrong and has to "redo" a bunch of stuff, $$$$...the good, your stuff will run better. To be honest, at this stage in the game, given the engine you've built and your hp goals, you are better off selling the Roe and going with a Paxton. You'll make more power and be happier with the car. Although a few have made low 700's with a roe setup, it usually required race gas and was seriously pushing the limits of the blower. I'm not sure how you could have ever thought you'd get 800rwhp out of it(considering no one else has) w/o a shot NOS.