T66 .96 a/r p-trim 20-26psi. comments/suggestions on what type or how big I should go on the intake side.

chuck

another pic

Don't forget to bevel the edge to 2mm to protect your apex seals from smashing into the closing edge of the port. Other wise they are nice and huge and will flow some serious exhaust. I tend to go a little smaller for street cars to help out with apex seal longevity. Nice job with porting to match your diffuser. Keep us updated with your results..

Put the 2mm bevel on them today. That took more effort then the porting.

Pic below is what my primary ports are, 90% done.

chuck

I wonder if there is any pro or con to leaving a sharp edge on the opening side of the exhaust port; where the apex seal "drops" over the side.



And what differences are noticed with a slightly elliptical (curved) closing edge versus a flat closing edge?

1: A sharp edge will "trip" the flow over the port, creating turbulence. You want a gradual opening on the edge, so the flow doesnt seperate from the runner wall.



2: Rounded exhaust ports have a broader torque curve, with the torque peak occuring at a lower rpm than squared off ports. Squared off porks make the engine more peaky, but have a stronger top end than rounded off ports.

Pic of secondary ports. Went up 5mm and out 2.5mm. S5 front and rear plate.

chuck

Another photo from the out side

chuck

Nature and the flow bench do not favor a sharp edge anywhere. You can nearly double the flow of a radiused edged hole over a sharp edged hole. At least a slight radius all around to protect the apex seal but the largest radius on the lower ramp.



Lynn E. Hanover

Nice work, Sleeper7. I'd love to see the results of this!



B

Looks very professional!

Excellent work, will we see the benefits of your labor anytime soon. Keep up the good work.

Taking the car to the dyno next week to get a base number with the stock 87 turboII motor. All the add ons are installed, T66, fuel upgrades, intercooler and exhaust. Then install the ported motor with everything else being the same to see the difference between the stock and ported motors. Now have a 3rd gen UIM and T-body waiting to be installed. My thinking is, dyno the car with the turboII UIM and T-body, install ported motor then dyno again, then install 3rd gen UIM and t-body and dyno again. Or would you guys like to see the difference in dyno numbers between the turboII UIM and t-body vs. the 3rd gen UIM and t-body. What do you guys think, if any one cares. All dyno runs will be at low boost, 20psi.

chuck

No dyno testing, saving the pennies.

The ported motor was installed today. Seat of the pants test felt really strong. I think this motor will cut my 1/4 mile times by .5 to .8 seconds. May be speaking out to early though. I am not one who "breaks in a motor", so it was heat cycled a few times then hit the road. Took it around the block, first and second gear only. 1st gear, clutch out, accelerate to 6000rpm's. Boost hit 10psi. Shift into second gear, no speed shift but kinda fast, then pushed it to the floor. Boost reached 15.6psi in second gear before 6500rpm's. The second gear pull took 1.7 seconds. Post a pic of datalog tomorrow. Using two used S5 rear rotor housings, end plates are S5, 2000mile atkins apex seals, S4 rotor with stock flywheel. Motor idles at 1000rpm's. vacuum is -10.5 psi after 45-60 minutes of run time. At times the motor will idle like a small bridge port depending on how much idle fuel. As of right now I am sold on going big on the exhaust. I just hope I did a good job on the exhaust port, not to cause the seals to wear prematurely. There is a bit more exhaust noise though, to be expected I guess. Well just thought I would share.



chuck

Well went to the dyno today. Very disappointed with my two runs but educational. Have some things to work out. Would not boost past 15psi in 5th gear all the way to 7000rpm's and running really rich.



Ranzo a forum member also did a few runs. 14psi and put down 370rwhp and 403 fwhp. His runs were so much faster and smother. Will post a dyno sheet of his runs when we get the printouts. Both car pulled in 5th gear. Ranzo's intake ports are the same as mine but my exhaust ports are bigger. He is running a TD06.



I ran first and you could not stay in the room because your eyes would start to burn. Ranzo's runs were so much cleaner. You could tell the was fuel in the air but it was bearable. Looks like I have lots of tuning to do but not bad for only running the motor for a week now with less then 5 running hours.

chuck

OK here is the graph from the Dyno that Sleeper7 is talking about. I was pleased with this run. We did two runs back to back and it pulled the same numbers on both runs with only slight differences in certain areas. I am using the exact same intake ports as Sleeper but the exhaust side is not as big because of the TDo6.



This was also using 720cc and 800cc injectors GT-R pump Trust FMIC and tuned with Power FC by me.