More results from my 3500Z!

[ForcedFirebird]

Johnny, your TGO link didn't work. Dave and I are both over there, though

[Superdave]

Thanks!

The aerochamber isn't on the car anymore. I put it on my truck a few months ago.

I'll probably end up running an electric cutout for the track and then just a decent crossflow Fbody muffler for the street. That should take care of any restriction and keep it somewhat tame on the street... With the car all torn apart for the winter i've been doing alot of planning for next spring, Other ideas include a whole new mandrel exhaust.. maybe true duals this time.

More on this as it gets closer to spring..

[johnnymossville]

Dave, do you know that you may be losing a few horsepower with your exhaust? I have been checking the net and have found out that to keep from losing hp in your exhaust your muffler needs to flow the same as a equal length of open pipe the same size as your exh. pipe. According to this Super Chevy article:

http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index.html

and this post by discostu in a thread (3" Exhaust) that you started:

Well knowing that your engine needs 2.2 cfm/hp of exhaust flow to not be a restriction, then it's easy after that...
350hp x 2.2 = 770cfm of exhaust flow for no restriction
We also know that straight pipe flows 115cfm per square inch of area...
770 / 115 = 6.70 square inches of exhaust area
And we know that the formula for area of a circle is pi * r * r
6.7 = 3.14 * r * r
6.7 / 3.14 = r * r
sqrt( 2.13 ) = r
r = 1.46" or the diameter of the pipe required is 2.92"...
3" pipe would be your best bet
Oh and don't forget to get a muffler to support 770 cfm of exhaust flow.
A Borla XR-1 would be your best bet, iirc the 3" flows in the 800cfm range...
Slowmasters are crap for flow, only like 400cfm. Magnaflows are better at around 650cfm.

http://www.thirdgen.org/techboard/ex...ml#post1699808

Down about half way is a comparison of muffler flow rates.

Edit:
Just as a subnote to this, if you were still planning the dual exhaust route... Go get the necessary 6.7 square inches of exhaust area, you'd need dual 2,1/8" pipe, not 2".
And if you go dual exhaust, make sure you include an exhaust H-pipe or X-pipe. It lowers the decibels by 1-3db and increases power by 5-10hp on a v8. That's basically free power folks, no downside whatsoever.

you should be running an exh. pipe 2.77 dia. with a muffler flowing 620.48 cfm. If you figure this with your 3 in. pipe you should have a muffler flowing 672 cfm for no hp loss in the exh. system. Another figure of say 315 hp (crank) x 2.2 = 693 cfm, hints that you may be losing hp. I know that your Hooker Aerochamber is a good muffler but I seriously doubt that it is flowing a minimum of 620 cfm and you probably need more than that.
The Super Chevy site also has some interesting info on secondary pipe (collector) length that you might find useful to squeeze a few more N/A hp out of the 3500Z.

[Superdave]

Bringing up an old thread I know. Someone mentioned your car in another thread I posted in, so I did a search and found this. I'm curious as to why that dyno chart appears the way it does. Also, your highest trap speed you posted here is only indicative of 230whp if the race weight stated in your profile is correct. Is that 2900lb race weight correct? What rpm do you shift the car at on the track? Also, you're only cutting 2.0 60ft times on drag radials? How do you launch the car?

I launch at about 2K-2500 RPM but i can't go WOT in 1st gear or it just spins the tires, it also spins for a sec going into 2nd and 3rd. Slicks should fix that, expect 1.x 60' times and very low 13's next year. I shift around 6500.


the dyno chart.. dunno, i've discussed it with the operator and he said that it was probably a mix of the AFR's being screwy, to much spark timing and now that i know my timing chain was stretched causing the exhaust valves to smack the pistons that might have been part of it.

The few runs i made after that one smoothed out a bit more with the AFR's leaning out, we didn't mess with the timing much on the dyno, just the VE tables. Next spring i'll hit the tuning hardcore with the few upgrades i have planned and go back to the dyno.

[mfewtrail]

Bringing up an old thread I know. Someone mentioned your car in another thread I posted in, so I did a search and found this. I'm curious as to why that dyno chart appears the way it does. Also, your highest trap speed you posted here is only indicative of 230whp if the race weight stated in your profile is correct. Is that 2900lb race weight correct? What rpm do you shift the car at on the track? Also, you're only cutting 2.0 60ft times on drag radials? How do you launch the car?

[PCGUY112887]

At least you can stay at a safe AFR at WOT... I still gotta do more scanning to fix my issues

[sprucegagt]

So refreshing to hear that the car is running faster as you get closer to 13.x AFR. I hear it too many times of people running in the 12.x range and lower while N/A, when complain that the car is not running up to potential. Even better to hear that your doing this with less timing. People never seem to understand that ignition timing has a sweet spot and it's not always advanced from the stock settings.

[Superdave]

tiny bit of KR at the end but not bad... I thought you said you were pulling 36* of timing... thats only 25 in that run...

i've been backing it off slowly.. with it so far advanced my AFR's were all over the place. Now it seems that the closer it gets to 13.x AFR, the more power it's making (like it should be).


I'll bump up the timing after the AFR's are where i want them, for now it's staying in the mid 20's...

[3400-95-Modified]

tiny bit of KR at the end but not bad... I thought you said you were pulling 36* of timing... thats only 25 in that run...

[Superdave]

Here is a datalog of the first 13.7 run (ran 2 of them)

Bigger TB will come soon, might not happen this season though...

[IsaacHayes]

Nice!!! have you decided if you are going to go with a 70mm or bigger TB yet?

[Superdave]

Drag radials.. i'm going to invest in a set of slicks ASAP.


Thanks! I need to find a power adapter for the laptop so i can keep tuning till it snows. It does have alot more in it, i'll post up a datalog section later on today for those interrested.

[johnnymossville]

You keep tuning and the 3500Z gets quicker! Great numbers Dave. What tires were you running?

[zofo61]

Dave....you are one of the few that has it right.......thanks for sharing your finds and please keep it up.............good job man....good job!!!!!!!

[Superdave]

new 1/4 mile time...

R/T .373
60' 2.075
330 5.904
1/8 8.943
MPH 83.79
1000 11.533
1/4 13.73
MPH 102.2