i dynoed my rx7 last week and i got 258 at 12psi. i think they are low numbers for what is in the car. i have greddy ic, pettit ecu, modded intake, boost control, water injection, msd, cat back, resonated midpipe, but i have stock dp. any ideas why low. i thought it would be the dp but a couple people told me it wasnt much difference.???

 

get the dp, you also might have a boost leak somewhere.

 

possible. ill check. i just didnt think it was that low. i wasted a vr4 the other day up to 150 and he had some parts. my car breaks loose in 1st and 2nd and once in a while in 3rd when the second turbo kicks in and i have 265 35-18s. i have noticed that alot of people dyno in 3rd gear. i dynoed in 4th make any difference???

 

When you say "stock downpipe", I assume you mean the stock pre-catalytic converter. I'm not sure I have ever heard of someone putting a mid pipe on and leaving on the pre-cat.

Your exhaust will flow only as fast as the most restrictive part of the system will allow. If you have the stock pre-cat, your mid pipe isn't being used to it's full potential. In fact, it's probably doing very little for you. If you put on a down pipe your exhaust will be greatly improved. You will also need to keep a close eye on boost and fuel.

Adam

 

yea stock pre cat. i bought the car like that i didnt pay attention to it. because the car was already fast so i assumed it was there. also he said it was gutted the stock dp/pre cat

 

That is pretty low. Can you post the dyno sheet? What did the A/F ratios look like?

 

at 12 psi with your mods, I'd imagine you'd be around 280-300 rwhp. If you post your sheet we might be able to see what's going on.

 

Yea, you should be close to 300. With the stock precat, your midpipe and cb aren't really doing anything extra for you. You're also keeping more heat in. Do a dp and you will be very happy just by the butt-o-meter.

 

The problem with your car is the dp..lose it. They are restrictive and they clog. When you remove it you should dyno ~320rwhp.

 

320 would be great. thats what im looking to get. ill post my dyno sheet after the new year im on vacation right now. i can explain some of it though . it increased normal,4800 jumped when the second turbos kicked in and hp and tq crossed at about 5800. my a/f was rich it was in the high 10s and then at high rpm 6k + its went below to high 9s low 10s. when i get the dp i will adjust it better maybe add a psi up to 13 to bring it to 11-11.5. just looking to get about 320rwhp.

 

is the greddy ic a fm or a sm? 320 should be feasible w/ a fmic, but pushing it w/ a smic.

 

Thats weird that your hp and torque crossed at 5800. The reason im saying that is because by definition of what horsepower is and what torque is they can only cross at 5252 rpm.

 

its a sm im looking for a fm greddy 2 row

 

i know i was expecting 5252, dont know why its 5800. it maybe a little less because i dont have the dyno sheet here in front of me but i know it was over 5500.

 

The reason i mentioned that is because if they did cross at 5800 then the dyno is just wrong. The dyno cant measure hp what it does is measure torque and then calculates hp based on a formula. Formula being torque at a specific rpm multiplied by the rpm divided by 5252. That is why at 5252 the hp and torque is the same. If for some reason their formula is messed up for the calculation and the hp and torque intersected at 5800 then what they're doing is torque times rpm divided by 5800 and at 6500 rpm that can give you a low hp rating by up to 30-40 hp, so in fact you can be pushing really high hp...

 

if you can tell me your peak hp and the rpm of the peak hp, and also the actual intersection point i can give you the actual hp numbers.

 

yea thats true they dyno could be messed up. what i will do is i will call someone to go to my house and give me everything exact. ill get the cross, highest tq and highest hp at whatever rpm they were at. ill post that tonight

 

Fact is your car could be running 300hp and the dyno said 258...in which case you should ask for your money back....

 

If you're squeeling your tires going into 3rd with 265s out back you have over 300 rwhp - 258 rwhp with your tires would spin in 1st and a little in 2nd but genieman17 is probably right on this one. Definitely get the DP though - lots of heat on those turbos -

 

what was ur A/f with pettit ecu?

 

When you say the torque and hp cross at 5800 rpm, look on both sides of the graph and make sure the scales for hp and torque are the same. Sometimes they are different, which will cause a different cross-over point (graphically speaking).

Also, what kind of dyno was it? A dynamic dyno will show less than a dyno jet.

EDIT: Oh, and for the love of god, get a downpipe on there!

 

I was going to ask those same two questions. I guess great minds think alike.

 

ok i got my dyno numbers. it crossed at 5850 rpm. made the 258.2 at 6500. and the torque was 242.8 at 5100. it was tested on a dynojet. anyway one of my friends read it off to me so i dont know if they are exactly right. they sound it but im not positive. whats the formula to find out how much hp i make? and the downpipe will be on as soon as i get back home.

 

A/F ratio PLEASE???

 

Ok well, I did out the calculation. If you are getting 258.2 @6500 that means that your torqe at 6500 multiplied by 6500 divided by 5850 (thats the crossing point) gives you the HP number. So if you reverse the calculation and divide 258.2 by 6500 and multiply that by 5850 you get the torque at 6500rpm which is 232.4. Now if you redo the HP calculation and multiply by 6500, but this time divide by 5252 (which by definition of torque and HP HAS to be the crossing point) you get 287.6HP. Now this calculation is right assuming one thing; that the crossing point was in fact 5850 and that the scales for the HP and torque graphsare the same, because if they're not it will only appear as though they intersect there.