38 replies to this topic

[Danny Steyn]

Just dynoing '99 engines with new restrictor plate. Was expecting around 2-4 HP loss, but in reality seeing 6-7HP on dynojet, even after tuning. Totally repeatable switching back and forth. Have we missed something?

What are you experiencing?

[Glenn]

Just dynoing '99 engines with new restrictor plate. Was expecting around 2-4 HP loss, but in reality seeing 6-7HP on dynojet, even after tuning. Totally repeatable switching back and forth. Have we missed something?

What are you experiencing?

New build or old car........

[Johnny D]

It's a gain (37mm) from NASA

Is it any faster on the dyno with 50# less weight?
J~

[James York]

Just dynoing '99 engines with new restrictor plate. Was expecting around 2-4 HP loss, but in reality seeing 6-7HP on dynojet, even after tuning. Totally repeatable switching back and forth. Have we missed something?

What are you experiencing?

Those numbers sound similar to what Drago posted a while ago about what was to be expected. Maybe 1 or 2 higher loss than the post.

Last year, when I tested the 37mm for giggles against the SCCA 41mm, I lost 6 to 7 hp reviewing my plots now. What's 1 mm? Not much, within dyno noise?

[Blake Clements]

I better stock up on 1.8 parts huh?

[Keith Andrews]

Sounds about right. I was at the dyno this weekend with a freshened motor. I'm hoping after my visit to Florida to go back and see if we gain anything.

I can't help with "Have we missed something?"

[Caveman-kwebb99]

Just dynoing '99 engines with new restrictor plate. Was expecting around 2-4 HP loss, but in reality seeing 6-7HP on dynojet, even after tuning. Totally repeatable switching back and forth. Have we missed something?

What are you experiencing?

Danny if you weren't so bizy hitting Charbs in the back bumper last year you would have been awake for this chat last year! My 99 and you have raced against it with 129.5hp in SCCA trim was only 124.5 in NASA trim. I am told that the higher the hp the eninge makes in SCCA trim the larger the hit to performance per mm of RP.

I only know of only one 1999 that was really cooking last year in NASA trim, it was driven by a refugee! I am 100% possitive that enigine would pass tech everytime! Aren't you engines from the same the builder? Pull some strings and get the better motor shipped to you this year!

I know that engine in the 99 was one hell of an engine last year, and this is no knock on driving tallent... he has plenty to spare! That car pulled the RP and could run down every straight with my 144.5 hp fully prepped PTE car in the PTE championship race, had it not been for a front hub failure I may very well be stiing in P4 rather than P3 at the finish.

So last year it was 5hp swing for me and if I had say 131hp it may have been more like a 6-7 hp swing like you are experiencing!

[Danny Steyn]

New build or old car........

Glenn - existing car - same day, same dyno, switching back and forth and tuning accordingly - 7HP repeatable loss.

[Jim Drago]

Just dynoing '99 engines with new restrictor plate. Was expecting around 2-4 HP loss, but in reality seeing 6-7HP on dynojet, even after tuning. Totally repeatable switching back and forth. Have we missed something?

What are you experiencing?

I' not sure why you ever expected only a 2-4 hp loss? I posted it was more than that as did most everyone else?

I suspect dyno practices a little bit, heat soak etc. If your not very careful, you can get conflicting results very easily. I'm not sure how they are doing the testing. Swapping plate in and out is the worst way of doing it. You have to make complete set of runs from 160-210 with 41m plate to warm the car, the fluids and drum grease etc.. let it cool.

Do again same way with 41 mm plate... let cool

install 38 mm plate run from 160-210, and see what you get.

throw away the high and low from each run and average the rest.



The average of our best was what I posted, 4-5 Hp. We developed a new exhaust and tuned it to the new plate and we are within 2-2.5 hp of what we had last year.

[Danny Steyn]

yup Kyle - missed it - kinda zoned out of the NASA discussion last year.

Must stay I was not expecting such a drop off. Silly me - the math says I should have anticipated more.

• 41mm - 38mm = 202mm² reduction or approx 8.5% reduction in area.
• 124HP - 117HP = 7HP reduction or approx 5.65% reduction in power (yesterdays numbers on dynojet on an existing engine being tested)

Well if this is what we can expect, then I think there will be a changing of the guard. At Road Atlanta I had nothing for Buras's new 1.6 motor in a straight line, even when in the draft. With a great Rossini engine, with 41mm plate. Would not have been pretty with 7Hp less.

Suspect that we will see several 1.6's being re-comissioned and I have it on good authoirty that the "talented refugee" of whom you speak has given up on the '99 and is re-commissioning his '94.

"Oh what have I done".... says Steyn as he writes another check to OPM for his new '99 build!!!

Edited by Danny Steyn, 12-21-2011 02:33 PM.

[Danny Steyn]

Thanks Jim for the dyno tips

will take this into consideration

[Jim Drago]

"Oh what have I done".... says Steyn as he writes another check to OPM for his new '99 build!!!

I wouldn't cancel that check just yet... You'll be fine!
You may get beat by Buras in a very good 1.6, Balanos or the chubby kid from Texas in a 97... But they should win races and would if we were all in 99's. I'm cautiously optimistic for 2012. I think the class will be really close.

[Blake Clements]

Where's David Dewhurst when you need him?

[Caveman-kwebb99]

He will be along momentarily, he is re-filling his popcorn bowl for a long drawn out chat about sm parityat Road America.

[Charlie Hayes]

I like reading this topic when I recently sold my 99' to build next season. NASA races last season against well prepped '99s,'01s, 1.6s and NA 1.8s were up for grabs by all 4 generations. Though I have no plans for SCCA National races due to the tires, but I will be giving the NASA champs a shot again and I hope every generation has a shot as well as the runoffs! Hope you can get it dialed though Danny.

[Danny Steyn]

Thanks Charlie - will not rest till its done.

[Blake Clements]

Danny, build them all.

[Danny Steyn]

Actually 2012 should be really FUN for everyone. Its gonna be all new for every model....

• How will the 1.6 do with the extra weight?
• How will the 1.6 deal with the extra rolling resistance of the Hoosiers?
• Will the 99's weight loss compensate for the horsepower loss?
• Will the '99 become competitive at tracks where weight used to kill the tires?
• Will the '01 emerge from the darkenss to be the sleeper many of us think it is?
• Will the '94-97 end up being the overdog that everyone is secretly thingking?
• Will the Hoosier close the field or open it up?

So many new things to work out - kind of exciting if you ask me! Traqmate will be your best buddy. Learning curve is gonna be steep

[Danny Steyn]

Blake - still not gonna make weight in a 1.6 with what i want in it - kinda knocks that one off the list

[FTodaro]

Last year I lost 6 hp between NASA and SCCA trim so I am expecting like only 5 this year if we are using the 41mm plate for last year as a bench mark. Danny' numbers are a bit high. Keep tuning.