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DIY Top End Porting

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Old 12-08-2017, 08:05 PM
  #81  
Dominic Sorresso
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It feels that way at times. The LT5 seems to always demand attention. But that is all forgotten with one wonderful drive.
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Old 12-08-2017, 09:55 PM
  #82  
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Originally Posted by KJL View Post
The day I can start a car following an extensive project the first time, I wil know hell as truly frozen over.
No joke. We feel your pain.

You will get it going. Let us know
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Old 12-17-2017, 02:57 PM
  #83  
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Originally Posted by KJL View Post
It appears that most of the primary boss can be removed from a 92 as well.
could the same be said for the '91?
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Old 12-17-2017, 03:39 PM
  #84  
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Originally Posted by ghlkal View Post
No joke. We feel your pain.

You will get it going. Let us know
Got it back together, turned the key and it still would not start. Got spark now and 45psi of fuel pressure. I pulled the chip and re-installed. It did not feel like it was seated all the way. Turned the key and she fired right up!!! Ran a little rough but soon smoothed out. I blocked the TB coolant lines so I need to run a few heat cycles to make sure she is full. I am getting coolant back though the small return line which is a good indication my pump is not air locked. I need to leave town for a couple of days but will take it out for a test drive later in the week.

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Old 12-17-2017, 04:03 PM
  #85  
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Originally Posted by jss06c6 View Post
could the same be said for the '91?
90-92 IHs are the same as far as injector bosses go.
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Old 12-17-2017, 08:28 PM
  #86  
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Originally Posted by KJL View Post
Turned the key and she fired right up!!!

Excellent!
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Old 12-22-2017, 07:42 AM
  #87  
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Originally Posted by KJL View Post
Paul-
My guess is there would be a small improvement in flow through the horn at high velocities. I just removed some casting impections and some of the sharp edges where the air transitions into the throttle body. My guess is the horn, given its size relative to everything else is not a pinch point for air flow. My little flow bench setup could not flow enough air to register any meaningful values for that.
Exactly... I
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Old 12-22-2017, 08:45 AM
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Originally Posted by ghlkal View Post
Excellent!
Took her out for a spin, ran great! Lots of seamless power. I will get it on a dyno soon to see see how much improvement. Almost got stopped by the cops. He was coming from the other direction as I was accelerating (not going fast) and I saw he put on his brakes so I quickly tapped mine to acknowledge I saw him. No issues. Many cops in the area are car nuts themselves. I have never been pulled over but received lots of smiles and thumbs up over the years. Now my pick up truck is a whole other story.....

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Old 03-13-2018, 11:31 AM
  #89  
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Putting it on the dyno tomorrow. Should be interesting to see if she does any better than the original run. Only upgrade is the port work, TB cooling delete, Secondary throttle blades locked open, new injectors and Marcs chip.
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Old 03-13-2018, 11:38 AM
  #90  
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Originally Posted by KJL View Post
Putting it on the dyno tomorrow. Should be interesting to see if she does any better than the original run. Only upgrade is the port work, TB cooling delete, Secondary throttle blades locked open, new injectors and Marcs chip.
I'm gonna guess...395-400 rwhp (Dynojet), once tuned (based on some others w/ similar work).
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Old 03-13-2018, 12:03 PM
  #91  
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Originally Posted by Paul Workman View Post
I'm gonna guess...395-400 rwhp (Dynojet), once tuned (based on some others w/ similar work).
Wow! That is what my 95 does. I suspect it will be somewhat lower. It originally dyno tested at 335 rwhp. My guess is around 350-355. My 95 has a better exhaust and headers. That first run is what happens when you forget to turn off the valet key.

I have that OBDI android app with the blue tube adapter. I plan on data logging the session as well.
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Old 03-14-2018, 04:41 PM
  #92  
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The numbers are in:
Upgrades:
Port Work as shown above
New Injectors
New Chip from Marc
Locked open secondary system

371 rwhp @ 5770 rpm +36 HP gain
362 rwtq @ 4860 rpm +30 ft-lb gain

Better than I expected. Headers and better exhaust would likely put me in the 390+ area which would be on par with my 95.
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Old 03-14-2018, 07:19 PM
  #93  
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My comment deals with where your power and torque peaks are. I believe they are on the low side of the rpm scale.
The image I have attached shows a comparison of progressive stages of modification w the bottom one being just ported top end and exhaust which is as close a compare I have to your setup.
Not trying to rain on your parade but it might suggest getting cams re-timed.
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Old 03-14-2018, 08:25 PM
  #94  
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The original run also seemed to peak a little early. It does appear that the peaks did move up the rpm scale a bit from the porting. I also performed a ALDLDroid data log of both runs. The second run we ran up to 6500 but the curve flattens out at 6000. I will get that curve tomorrow and post it as well.

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Old 03-15-2018, 10:57 AM
  #95  
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Originally Posted by KJL View Post
The original run also seemed to peak a little early. It does appear that the peaks did move up the rpm scale a bit from the porting. I also performed a ALDLDroid data log of both runs. The second run we ran up to 6500 but the curve flattens out at 6000. I will get that curve tomorrow and post it as well.
I agree w/ Dom. Cam phasing is key. And, unless the A/F was going too lean, why the 6500 cutoff?? Power was still on the ascension part of the curve! Sometimes I had to tell the dyno 'driver' to run it out till the shift light (set at 7100 rpm) came on. Otherwise (many) tend to cut it off based on habit/sound (I found out early).

Below is my LT5 - pretty much the same setup as Dom's, except the cams are stock. But, look at how the power/torque curve patterns compare (supporting Dom's comments).

.
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Old 03-15-2018, 12:06 PM
  #96  
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Thanks for the feedback. It is a stock engine with 21,000 miles on it. If it has a phasing issue, it likely came from the factory that way. I am going to review the other curve and may re-run it to a higher rpm. If Dom is willing to review my data log that would be great. Either way if it is a phasing issue then I will likely have to live it until the next time I get bored and decide to pull the engine. Not many people around here know much about these cars
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Old 03-15-2018, 12:26 PM
  #97  
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Sent pm
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Old 03-16-2018, 10:59 AM
  #98  
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Dom did some great tuning work on my car. As for mechanical work I understand one of the better Z shops is back in business.

South Georgia Corvettes, 1396 Dillon Rd, Thomasville, GA 31757
229-403-7009

H
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Old 03-18-2018, 06:31 PM
  #99  
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Originally Posted by ccmano View Post
Dom did some great tuning work on my car. As for mechanical work I understand one of the better Z shops is back in business.

South Georgia Corvettes, 1396 Dillon Rd, Thomasville, GA 31757
229-403-7009

H
Thanks for the info. I am probably going to leave the car alone for now. It runs so well. Like a new car. My 95 is my play car. I am seriously considering one of Pete's engine conversions. I am planning on running that car next with data logs and O2 data so Hopefully Dom can tune a few extra ponies into her before I pull the trigger on an engine upgrade.
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Old 03-19-2018, 03:01 PM
  #100  
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Originally Posted by ccmano View Post
Dom did some great tuning work on my car. As for mechanical work I understand one of the better Z shops is back in business.

South Georgia Corvettes, 1396 Dillon Rd, Thomasville, GA 31757
229-403-7009

H
Aaron's back?

Brian A.
90 ZR-1
[email protected]
01 Z06
not quite stock
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