Just got back from the dyno this afternoon working on a buddy's car. His is an 87 Turbo II with one of my half-bridgeport setups on a series 4 turbo motor using a Master Power T70 w/ a 1.15 A/R hotside, a Haltech E6K, 720/1680 injector combo, and a Mk4 Toyota Supra fuel pump. This is the 2nd time the car has been to the dyno. Today was over 90 degrees and humid; not a good day to dyno. The schedule was a bit impromptu and we weren't prepared for everything.



We dyno'd the car two months ago and it made 434rwhp at 19-20psi. It did very well in the lower RPM's. The car, however, had a big problem with the exhaust at the time, running a 3" downpipe and midpipe to a 2.5" pipe w/ secondary, "box" muffler. It was producing alot of backpressure. We had it fixed and were going to see what it would do today.



It was making good power; 460's, 470's, and eventually hit 480.8rwhp at 21psi of boost. Problems today:



- Had alot of breakup and shaky up/down power at higher RPM's under load.

- Couldn't get over 22psi although it was mainly sitting around 20-21psi the entire time (I wanted to push it to 25-27psi and stretch that turbo out some)



I believe the break-up was due to old spark plugs. We just forgot to change them out; they've been through one rebuild as well as months and months of driving and tuning. There's no telling what kind of shape they're in. Using BUR9EQ's all around. I'm not sure what was causing the lack of overall boost but I believe it's an air leak somewhere. We haven't tested the blow off valve to see if the spring is too loose. Also, he may be leaking air out on one of the intake manifold gaskets.



The air/fuel ratios were kept at a moderate 12:1 thereabouts under load with race gas, and were steady, so I can't attribute it to the jumps in power. The car felt damn powerful on the way home; a high 10 second 1/4mi slip I think will be possible with it. No problems with shakiness of power or breakup on the road.



Here's a link to the pics and videos:



http://bdc.genxracing.com/Videos/DynoDay_060705



Thanks to Klar for coming out to lend us a 3rd hand with the water sprayer, camera, and Hawk eyes. It was damn hot today!!!!! Hope to break 500's soon.



More to come later ...



B

nice...Hummm I'm going to need some tuning on my project care when I get home from Afghanistan...will you travle?

try NGK # R6725-105 or R6725-11 race plugs.

[quote name='Nospig' date='Jun 8 2005, 03:17 AM']try NGK # R6725-105 or R6725-11 race plugs.


[/quote]



The thing just needed new plugs. Maybe we ought to get a set of 10.5's for the leadings just for dyno day. But, the 9's will work just fine for this power level and heat range. 11.5's are pretty cold; I don't think we have a need for them yet.



B

[quote name='Midnightdriver' date='Jun 7 2005, 10:07 PM']nice...Hummm I'm going to need some tuning on my project care when I get home from Afghanistan...will you travle?


[/quote]



Yep, I do it all of the time. Shoot me a PM.



B

wow, thats kickass bdc. Wish I was closer to Ft. Worth https://www.nopistons.com/forums/pub...DIR#>/wink.png

awsome.

[quote name='Nospig' date='Jun 8 2005, 03:17 AM']try NGK # R6725-105 or R6725-11 race plugs.


[/quote]





I tried some NGK R6252E-105's in my N/A 12aBP. They wouldnt run on the motor. The car would stutter and spit when loaded. I had to go back to the factory style plug. I've never seen the R6725-105's, do they have 4 ground straps or just one. The plug I tried has only one ground strap, and I wasnt sure if this was my problem. I was trying colder plugs so I could be safe when using nitrous.

Here is a pic of the race plug next to a stocker.

By the way. What rpm does it make peak power with the half bridge? Would you share any pics of what the port looks like? I'm assuming it uses the stock intake manifold, correct? Does the bridge cut into the rotor housing?