I have been searching the forum trying to find someone with some actual experience runing Comp Turbo's 8079 turbo. I cant find much info. All i can seem to find is the thread where someone was having back pressure issues and that was scaring people into running differnet setups or totally different turbos.

I just purcahsed a Comp 8079 with a 1.15 AR, a 3.5" DP, and a NON-billet wheel. I am curious if anyone had any real life experince running this turbo. My goals are nothing out of this world. I have a LQ4 bottom end with LS3 heads and intake. Runnign a 232/234 .595.598 @112 cam and i am shooting for around 700whp or a tick more.

So lets hear some info that you guys have. Like it, hate it, had this issue or that issue, or does it work perfectly as you would expect. Any info would be appriciated. Thanks.

 

We have quite a few customers running the 7679s and 7879s with great results. We don't sell many of the 8079s as the compressor wheel simply outflows the turbine side too much making it not as efficient of a set-up. The 7679 and 7879 seem to be much better matched to our higher displacement engines. Should still work great and have no problem hitting your 700 rwhp mark however. Enjoy it, Comp makes a nice turbo!

 

I have been reading that about the compresser wheel flowing more then the turbine wheel. However, i was lead to believe that was the case with the billet wheels and not so much the case with the cast compressor wheel. Do you believe there is any truth to this or would both wheels have the same issue with backpressure.

 

I ran the Comp CT43-8079 triple ball bearing single on a 357W Ford. Just 12lbs and pump gas made 595 RWHP on a Mustang Dyno, off the wastegate spring. I was planning to run 16-18lbs but sold the car. Should have been well into the 600's if not 700 when I was done.

was a stock bottom end with forged pistons and Performer RPM heads. Carb'd Blow Thru. C-4 auto trans

I think your goal is easily attainable

 

That was me with the bp issues. With a billet wheel it had 4:1 bp. With the cast it had 2:1.

With the cast i made 775whp,locked auto and 9inch on 18psi. It wouldn't make power past about 5400rpm. Ran 10.1 @138 @ 3800lbs

 

Now I have a ct43comp cover on a ct5, 88mm comp, 94/88 turbine. Same mph 138 but went 9.8. Made 100 more wheel hp but still not making more power past 5400rpm. Probably something else causing that issue.

 

So the cast wheel did fix your issue that you were having. I never did get the details on how you had it fixed but did see the issue was solved.

 

Ya going from 4:1 to 2:1 was putting the cast wheel in it. Now with the ct5 hybrid I'm at about 1.5:1. But 2:1 is ok with a t4 turbo

 

For just some follow up info. This setup finally made it on the dyno. I had some boost controller issues so we could just dyno it on 6psi. On 6lbs the car put down 501whp / 496 tq.

Since the dyno I have upped the boost and am pleasantly pleased with how fast the turbo spools and the power it makes. I have yet to go back to the dyno to see what power is at with the higher boost levels.

 

What sort of efficiency are we talking about here when you say the 8079 isn't as efficient as the 7679 or 7879?

 

So what turbo did you end up with? What size motor and what kind of rpm did it start to drop off in power?

 

I did not get a dyno sheet. There was a lot going on that day and I spaced it off actually (hard to imagine I know). I went with the Comp CT 43 8079 with a 3.5" DP and 1.15AR. NON billet wheel as well. Oil cooled only turbo.

The motor its on is a Stock bottom LQ4 with a LS3 topened.

I will have to see if I can get a copy of the sheet. I am unsure if I can or if the file would have been deleted. However I do know the turbo was not struggleing at all. Spools instantly and Pulled really well to redline.

 

So, back on this topic. I have been greatly pleased with the turbo. I have done mostly street driving and have not had a chance to get a good solid track pass in. However, the best pass i have had to date, i ended up having a piston let loose and in the process i belive the turbo is in need of a rebuild.

SO, here is my question. If i need to rebuild the turbo, would it be worth it to replace the exhaust side wheel with something a little different that will still fit in the housing that i have? I have heard of peopel upping the size of the 79 wheel to something a little larger. Does anyone have any thoughts on this.?

Here is a copy of my slip. you can tell i had issues jsut after the 1/8th mile. only gained 12 mph on the back half. The car has a ton more in it off the line and boost wise as well. this was on 13psi.

 

just because I honestly don't know, is BP measured at the manifold between the head and the turbo?
Would using a larger AR turbine housing cure this issue?

 

It's measureD in the exhaust before the turbo. Larger AR helps but is not the cure. Smaller engine or bigger turbine wheel