Xenogenesis402

Hey everyone, i've got an 87 N/A ITS rx-7 that has been running really slow on the straights but handles amazingly. Well we took it to a shop here in miami and got it dyno tuned. When it came in there it had 146 to the wheels and was running PIG rich. When we left the shop after a/f, timing, intake manifold, and stock computer tuning, it has 193whp. Is that about right for a car that is basically at it's legal limits for the ITS class? We still have the stock computer and i know there is a bunch of HP sleeping there. Thanks guys.

Eagle7

Congratulations on the major improvement. I've gone through a similar tuning experience and tracked the car with the newfound HP the first time this past weekend. It's awfully refreshing to not see the leaders vanishing down the straightaway.

Where did you end up with AFR and timing? Were you able to get a relatively flat AFR curve with the stock ECU? S4 or S5 setup?

I think I'd question your dyno calibration (or your legality). With that number you'd probably have the highest known HP in the country for an ITS RX-7.

Have fun,

Xenogenesis402

Do you really think so? We just got our motor rebuilt probably about 6-8 months ago and the guy said he did everything legal to it. Now that dyno might read high compared to Dynojets or something. I think the dyno machine was a Dyno Dynamic? I've actually never heard of that kind of dyno since all my vehicles get placed on the Dynojets.

the a/f was relatively flat until the upper RPM area, like 6k or so, then it started to richen up.

And by S4 or S5 setup, what do you mean? I'm still uber noob when it comes to these RX-7 lingo's and acronyms. lol.

Thanks for the reply, i have a feeling that dyno just reads high, probably just the opposite of the Mustang dyno's.

Eagle7

S4 is an '86-'88, S5 is '89-'91. They have different ECUs, air flow meters, harnesses, oil metering pump, etc.

moremazda

iTrader: (4)

Isn't ITS a stock port class?? 193hp sounds high for a S5 street port, so I would question the calibration of the dyno....

DriveFast7

iTrader: (1)

IT is a stock port class.

We've seen on this forum that a 1st gen GSL-SE that is ITS legal with stock ports, air filter, good street exhaust and no smog puts 145 to the ground for comparison sake.

Different motor sure, but a starting point for benchmark.

Could you lower the fuel pressure some to help with high rpm richness?

Isn't redone ECU's legal in ITS if it fits in the stock ECU box?

Sounds like a healthy motor either way.

Xenogenesis402

I'm pretty sure that the car (According to the VIN) is a 1987 so it'd be S4. But the motor was rebuilt completely with 89 and 91 parts. The car had 0 port work done or anything. We told him that whatever he is going to do in the rebuild make sure it complies w/ the GCR for IT classes.

And we did play w/ the fuel pressure and that's where we got the car to jump over the 190 barrier. We just couldn't control the top RPM a/f without leaning out the lower end. The drawbacks of having the stock ECU for tuning (of what little there was to tune!)

The guy said that if we were to go aftermarket ECU (which yes it is legal in ITS so long as it fits inside the stock ECU housing and uses the stock ECU harness) that we should go w/ a Micro____. I forget the second part lol. Microtune or Microcomp or something. Apparently it fits inside the stock housing and uses the stock harness.

I just pray that the guy who built our motor did it to legal specs. I know for sure he didn't do any port work because he didn't have any of the machines to do it. (one of those 'do it out of the garage' type of guys).

Thanks for the responses guys! Sounds like that if the car is for sure 100% legal then it seems to be a freak. If we take a look inside the motor itself, what should we look for incase something is infact not to spec?

Eagle7

There's documentation of legal ITS cars exceeding 180 HP on a DynoJet, but 190+ is pretty unlikely. Mine managed 160 on a Mustang.

its66

iTrader: (2)

With 89 rotors, housing, and intake manifold, AND a Great exhaust system, High 160's is the norm. High dollar seals and extensive dyno tuning can often result in breaking into low/mid 170's. Combine all this with an aftermarket ECU, and a perfect day, you might get 180-183.

I suspect something is wrong with the dyno, or someone took a liberal interpretation of IMPROVED touring.

What do you have for exhaust? 89+ intake?

AS far as what to look for--were the housing new? Used housing may have been ported prior to becoming part of your engine. The exhaust port should have a deflector in it. I believe it would be illegal to remove it.

Before I did anything, I would take it to a different shop to have it redyno'd. Someone with a dynojet who has done pulls on ITS cars before. That way you will have a comparison. There are several ITS racers in your area, surely they have also used local dynos. There is also a big mazda shop down there in Sunrise. They know absolutely what an ITS RX7 will pull on their dyno. It might be tough to get dyno time scheduled with them though. They are pretty busy trying to defend their Grand Am championships and developing the 3rotor GT car.

Xenogenesis402

Well i'm definitely going to take it to a Dynojet to get some comparison numbers.

Has anyone ever had experience with a Dyno Dynamics machine? I've personally never heard of one of those. The exhaust is a full ISC racing system. From the headers back. The intake manifold looks to be stock although maybe taking it off to see for porting wouldn't hurt. This really blows that i have to check my own damn car for legality issues. But i'm not gonna do any major anything until i get it put on a dynojet.

Hey, quick question for you ITS guys, do the physical headlights need to be installed or are they able to be removed? My dad and I have been going through the GCR to make sure this stupid car has all of the BS legality issues taken care of.

Thanks for the help!

wrankin

That's probably your best first bet.

Yes, headlights and the other front assemblies (including all the lenses) must be on the car. When going through the GCR, IIDSYCTYC applies (If it doesn't sat you can, then you can't)

Probably the most confusing section of the GCR (to me at least) was the one on front air dams and air ducts.

Good luck with everything,

-bill

Xenogenesis402

Yeah i learned that quickly w/ the GCR. hehe. Ok then i need to pick up some factory headlights. See, unfortunately/fortunately i bought the car used (already race prepped and everything) so when we got it we had no clue what was legal and what wasn't and all that crap. So Now that we at least know our car has gained power, we want to make sure we wont get thrown out for something as stupid as like... having to have all the heater hoses in place but not having to be hooked up.

Either way, i wan't to make sure the car is 100% legal, even though i know cheating is rampant i'd rather not participate. Raced go-karts for 12 years w/o cheating, why start now? lol.

thanks again.

Kyle #42

crispeed

The Dynodynamics dyno reads lower than the Dynojet if the correction factor is set to the industry standard of 1.0.
Now most shops that I know of set the correction factor to read the same as Dynojet #'s.
The problem with that is that no one really knows what the correction factor for each car is and results are going to vary.
All that don't matter when you're using a dyno unless it's for bragging rights. What matters the most is the difference you see from your first pass to your last.
It's very easy to inflate horsepower #'s on a Dynodynamics by changing the correction factor.
The Dynodynamics is a much better dyno to tune on vs the old Dynojet dynos and that's due to the ability of the Dynodynamics to apply load although the new Dynojets have the same feature I have not seen one in this town as of yet.
I guess your lap times is going to show the horsepower.
That's the only factor you can't cheat on

DriveFast7

iTrader: (1)

Why not just remove the intake and exhaust manifolds, and borrow the local SCCA tech inspector's lollipop's to test port sizes?

If that's not available you can make or measure your own from a junker motor.

Only cost a couple of gaskets and not much time. Don't even have to put the car on the trailer....

RETed

That's what some of the top running IT-S FC's are running.
I've heard that Tremblay and company down at SpeedSource are getting their IT-S's into the 200 to 220 hp range *at the wheels*!


-Ted

C. Ludwig

iTrader: (27)

You've heard wrong.

Eagle7

Why don't you call Sylvain and check that out personally. He's a very approachable guy.

crispeed

Yeh!
I use to hear the same thing also. That's even more than he got in the begginning with the stock rx-8 motor using a Motec ecu.
But you know how it goes in IT. No one really knows how stock it is untill you pull it. It also depends on who is responsible for inspections and tear down.
Now did I just say that!

peejay

Even if the dyno is off, it's still roughly 33-35% more power, unless the tuning also included tuning the dyno.

C. Ludwig

iTrader: (27)

Really he's only claiming about 10% over what the top dogs are making. Speedsource has claimed 175 whp with stock electronics for years. That number has went up somewhere around 10 whp with the addition of the Motec. Let's just say that all the extra power found with the Motec isn't all in the ability to pinpoint the a/f and timing. Gray areas were opened with that rule change that were never intended. That 175 whp claim is so reliable that it's used as the bogey number for power/weight comparisons to every other car in ITS by IT rules committee.

I've seen and heard dyno numbers of ITS RX-7s ranging from the 140 range to the low 180s. Never heard 190+. All the hot cars are generally claiming within 10 hp of each other and IMO that is within the variance of one dyno to the next. It all goes back to the same, age old dyno debate. It's a tuning tool. Set your baseline and then go to work until you find repeatable gains. In short the original claims are either optimistic relative to every other ITS engine in the country, the package isn't legal, or the dyno isn't properly calibrated. Either way that number won't mean a hill of beans to the stopwatch.

Eagle7

I think peejay meant that Xeno improved by 33% while at the dyno. Forget any other comparisons, it was a huge improvement - way to go.

C. Ludwig

iTrader: (27)

You're probably right.

Xenogenesis402

Well thanks to you all for the good information and encouragement, i had a feeling that 193whp was a little high but that was because i didn't know what a fast its RX-7 whp was. The car is going on a Dynojet in about 3 weeks. I'll post the results in here just to get a baseline and what not.

Either way, if the dyno is even 20whp off, like what peejay and eagle said, it's still a considerable improvement and now i'm gonna have to adjust my braking points at homestead this weekend. lol Thanks again guys i'll let yall know what the dyno results are and hopefully i'll get a good finish @ the homestead ECR enduro this weekend!

C. Ludwig

iTrader: (27)

Good luck! Let us know what kind of a difference you see in lap times.

Xenogenesis402

Well overall we dropped about 2 seconds off our last time there without pushing the car much. We had some really bad overheating problems that needs to be addressed before the next race. So unfortunately i wasn't able to push the car that hard or else the temps would go bonkers.

Anyways we qualified 12 overall and 5th in class out of about 40'something cars. The race started in the rain so we had our ol' trusty toyo's for the rain. Made our way up to 3rd IC position and were running right there w/ the guys that usually maul us. The speedsource cars now only pull us some down the straights instead of embarrassingly. Luckly i can make up that time in the turns. So we're doing great the car is running a little hot but nothing dangerous and it comes time for our pitstop. We pit in and get ready to do a tire switch because the racing line was dry at this point. Take off the left rear no problem, our pitcrew guy was breaking the right side lugs loose for easy removal until we got to the left front. We're breaking the lugs loose when one of them goes soft. The damn thing stripped. The outside of the lug was basically round with a few high spots. So we were in the pits for almost 7 or 8 minutes because we were fumbling with that ****. So I had to finish the race on rain tires and we fell back pretty far, i dont even know where. It really sucked but at least the car was running good. If only we weren't overheating we would have done better in the beginning.

Back to the drawing board.