well I finally got all the bugs worked out of the car and got it back to the Dyno. The results were pretty disappointing compared to what many are getting here with my mods. The car made 409 rwhp and about 380 tq. I do not have the graph with me so I can not post it sorry. AFR was around 13to1

My specs are as follows.

1993 Mazda RX7 with 02 Camaro LS1 swap.
Stock cubes with flycut pistons about a nickle deep. Arp rod bolts
CNC ported 243 heads with 2.055int and 1.60 exh. Intake runner about 225cc and 64cc chamber size. Done by Pete at CNC heads St Pete FL
Jesel 1.7 shaft mount rockers
Patriot dual extreme springs shimmed to 1.78"
.040 cometic gaskets
7.45 comp pushrods
Caddy race lifters preload about .060
comp XE-R 232/236 .595/.601 114+4 cam
ported stock TB
85mm MaF
LS6 intake Mani
38# injectors and high flow pump(pressure solid at 58psi)
1 3/4 Long tube headers from JTR. Dual 3" into single 3" with center resonator and 3" straight through cat back exhaust.
T56 out of camaro with aluminum LS2 flywheel and LS7 clutch and PP.
aluminum drive shaft and 4.11 Mazda rear end.
No power steering or AC
Rear tire size of 285/30-18

My friend with the same car, same cam, same TB, same headers, made 404hp with stock 241 heads, stock rockers, stock lifters, stock PR's, stock MAF. His exhaust was dual 3" into single 4" with single magnaflow can at the rear.

Our other friend with a 99 vette, made about the same HP with this same cam and dual 3" exhaust and stock 853 heads. I think both are running comp 921 springs.

My car should be putting down 430-440 hp with the heads. This seems to be pretty consistant with what I see here. Could the difference be all in the exhaust. I thought many Camaro guys achieved the mid 400's with dual 3" to single 3".

What gives. We are in the process of trouble shooting but figured I would try to get some input here.

Thanks
Mike

 

two of my friends has low dyno numbers and they beat higher dyno numbered cars on races from a roll (choose a speed that you both will not spin that much or not spin at all) .... race your friend that has the same cam and if you didn`t beat him by at least 2-3 cars in a 1/2 a mile a head then there`s something wrong.

I know three cammed cars and non of them reach many numbers posted with less cam or mods including myself .... and as they : say take it to the track and see what she does , a dyno is a tuning tool (although me too would like to have a high number)

 

I plan on getting to the track next week hopefully. If my trap speeds are good then I will be happy. I know it is just a number and all, but I wonder if it is indicative of a problem or mismatch in parts. Everybody says that this seems low for the mods I have. We will see once I get it to the strip.

BTW, are you still in Kuwait. A good friend of mine here in Tampa, who also has a LS1 Rx7, is from there. He exports a lot of cars back to Kuwait. Many fox body Mustangs and Yukons over there are from him. God only knows how many guys are street racing in all the Mustangs he has sent. I plan on going one time when he goes back to visit.

check out www.q8speed.com

Mike

 

My only comment is that 225cc heads seem large for a 346 motor.

 

What he said...take her to a track and see what she does. The only other thing I can think of is that the intake manifold is choking the motor....although I don't usually see that until 420-430rwhp on our Mustang Dyno.

 

yeah I`m in Kuwait ... and never saw that site before sorry might be just me.

and what he said too about the intake manifold usaully many cars here with 430-450 hp uses a fast 90 and sometimes a ported fast and that also helps alot.

the others are milled heads for a raised copression wich helps too so does a tighter lsa 112-110 +2 to 4 (maybe lsa just changes the power band correct me if I`m wrong)

 

Would this only be a downside for low/midrange power, or does it hurt top end as well. I would think the extra size would help ultimate flow. Also, aren't many of the 243 ported heads on here around 225cc as well(patriot,tsp). I know the aftermarkets like AFR and EtP are 205/210, but most heads that start off as 243 type heads are around 225cc. Just a thought

Mike

 

i think you need to mil the heads. your compression is close to stock still so i would think if it were in the 11 to 1 range it would make the power you want.

also make sure you have the right size pushrods. that could cause lower numbers. maybe you could use some more tuning..... not sure but it does seem like it should make atleast 430. but every car is different so. try a different dyno also that wouldnt hurt

just some ideas

 

75mm stock tb and manifold isnt going to help

 

There aren't too many heads that offer a runner smaller than 225cc. I'm pretty sure TEA 5.3's have a 225cc runner and they make great power on 346 motors.

To the thread starter: why did you flycut? It seems to me that that cam would fit just fine without notching the pistons. You need more compression. A ported FAST 90 would also help to raise your numbers.

You should try and get a hold of the graph and post it for us to see.

 

hey everyone, sorry for not following up sooner. In response to some of the tips posted above.

1)i think you need to mil the heads. your compression is close to stock still so i would think if it were in the 11 to 1 range it would make the power you want.

I figure I am around 10.5 to 1 with these heads and head gasket. How much more can I get from only a .5 bump in compression. Also, both guys who dynoed close to my numbers were running stock heads at 67cc(241 castings) and stock ls6 intake manifolds. Stock .056 gaskets and also Flycut.

2)also make sure you have the right size pushrods. that could cause lower numbers. maybe you could use some more tuning..... not sure but it does seem like it should make atleast 430. but every car is different so. try a different dyno also that wouldnt hurt

Pushrod lengths have been checked. I get approximately .050-.060 preload on the caddy lifters. Car has been on two different dynos and has been tuned to 13 to 1 AFR. 1st dyno maxed at 404hp at 6k where it fell off due to valve float. 2nd time on different dyno maxed 409rwhp at 6600 rpm with no valve float due to new springs. Air fuels were good.

3)What he said...take her to a track and see what she does. The only other thing I can think of is that the intake manifold is choking the motor....although I don't usually see that until 420-430rwhp on our Mustang Dyno.

Mustang dynos read lower than dynojet so that should corrolate to around 460 on a dynojet. This seems about right for a fast intake. 430-440 on dynojet should be fine for a ls6 mani and ported TB. Also, we watched vacuum and it stayed within limits throughout the pull.

4)75mm stock tb and manifold isnt going to help

It is ported to 78mm. this was what my friends had when they dynoed 404. Both guys had a stock 75mm Maf's instead of the 85mm.

5)To the thread starter: why did you flycut? It seems to me that that cam would fit just fine without notching the pistons. You need more compression. A ported FAST 90 would also help to raise your numbers.

we did the flycut to be safe because of the larger valves and thinner gasket. My understanding is that flycutting, while creating more cc's, does not affect compression the same as if the same cc's were added to the chamber. Also lowering the head and increasing quench makes up for it. I could be wrong.

Just so everyone knows, I appreciate all the help. There are many good suggestions as to how to gain more power. My concern for the most part is why am I not seeing in the 430 range with what I already have. Especially when similar builds are putting down the same power with less compression and stock heads.

I plan to check compression this weekend. What should a healy motor see number wise.

Mike

Bader, are you the guy who came to my wheel shop in Tampa with an RX7.

 

I got dizzy reading through the answers and questions

Hogged out heads don't always flow better; not to knock Pete . . . but I know from experience

Compression is probably too low. Intake and tb . . . all of which have already been mentioned

My opinion for the culprit of the missing power is in the Head.

Without going into too much detail, 4 years ago I used to spank the **** out of my buddies old '02 WS6 with comparable bolt-ons but he had a bigger cam, more compression, and Pete's hogged out LS6 Heads compared to my old school Stage 2 LS1 heads at the time. The "spanking" occured during roll races; a better measure of power on the street.

You will pick up some more power on top of your current results from a 90/90 set-up and Head milling.

Good luck

 

No I`m not but he seems like a cool guy with lots of friends out there ... and loves Ls1`s you`re the second guy that asks me if I`m him or I know him.

 

numbers look normal for what you have, also depends on what the heads can do.

Get rid of that clutch and you have another 10-12 hp/tq to pick up.