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Not building boost
Posted: Tue Sep 17, 2019 2:18 pm
by Booky
Have GT15 on a 1600 cc can not get above 2lbs of boost could the turbo be to small.
Re: Not building boost
Posted: Tue Sep 17, 2019 2:46 pm
by Schweg
Doesn’t sound like it just googling that turbo. Draw through? Blow through? EFI? What’s the set up?
When are you seeing the 2psi?
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Re: Not building boost
Posted: Tue Sep 17, 2019 3:18 pm
by Booky
Blow through seeing boosts about 2300 rpms and I’m blowing through Kadrons.
Re: Not building boost
Posted: Tue Sep 17, 2019 3:52 pm
by panel
What kind of wastegate on your project ? Internal or external ? Are you running any kind of boost controller ?
Don't hold back on the info/specs etc
Re: Not building boost
Posted: Tue Sep 17, 2019 4:15 pm
by Booky
Internally waste gate no boost controller turbo came off a Hunday sports car they were I think up to 1.8.I have been all over every connection to make sure it’s not leaking.
Re: Not building boost
Posted: Tue Sep 17, 2019 4:24 pm
by Schweg
Where are you pulling your boost gauge reading from?
Is your fuel pressure regulator boost referenced?
What are you using to time ignition?
Have you checked header flanges? I had one that had rattled the nuts off and I was barely making boost. Also the above questions.
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Re: Not building boost
Posted: Tue Sep 17, 2019 4:50 pm
by Booky
Boost reference for gage and fuel pump are coming from the port on the turbo. I have a cb Performance digital distributor for right now using there 7# boost program. Yes have looked at all connections 2 or 3 times and had someone else check them to.
Re: Not building boost
Posted: Tue Sep 17, 2019 4:57 pm
by Booky
I’m using cb performance graphite gaskets on all the exhaust joints but I will double check tomorrow.
Re: Not building boost
Posted: Tue Sep 17, 2019 4:58 pm
by Schweg
Have you changed the jetting in your carbs? Are you Monitering AFR?
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Re: Not building boost
Posted: Tue Sep 17, 2019 5:48 pm
by Booky
Yes to both afr at boost and wide open running around 12.1 to 13.5. running 55 on idle jet 130 on main jet and I boost referenced the float bowl.
Re: Not building boost
Posted: Tue Sep 17, 2019 7:13 pm
by Schweg
How old are the pistons and cylinders? Ring blow by? Have you run a compression or a bleed down?
This is not a great plan but.... you could try running it with the waste gate disconnected. Being very gentle to not push yourself out of a safe AFR. At least then you can verify if the waste gate is set correct or not.
It sounds like you have everything else and have checked all items. An engine photo or two may help if something is plumbed incorrectly.
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Re: Not building boost
Posted: Tue Sep 17, 2019 7:17 pm
by Booky
I did a compression test 120 all the way around did not do leak down test. I have not tested the waste gate yet I will do that tomorrow.
Re: Not building boost
Posted: Tue Sep 17, 2019 7:36 pm
by buguy
With that little turbo you should be getting plenty of boost. I'd guess the waste gate is bleeding off pressure or you have a header leaking. Can you spin your turbo with your finger?
Re: Not building boost
Posted: Tue Sep 17, 2019 8:17 pm
by Booky
Yes very easy to spin.With the questions that were being asked I am wondering if my waste gate might be bad and opening up under low boost like has been suggested.
Re: Not building boost
Posted: Wed Sep 18, 2019 12:21 am
by bug66
Are you actually driving it, or just free revving it in neutral?
Use a highly flammable spray to find the vacuum leak if there is any. Something is wrong
