ignition curves for turbo engines
07-07-2015 | 10:06 PM
#12
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From: Northport N.Y.
08-07-2015 | 08:09 AM
#13
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From: St. Clair Shores, MI
14 Apache, TurboJack or anybody else that has run a twin turbo draw thru system. Has anybody run a wide band O2 sensor in your system? I have one on each right hand exhaust pipe about 6 inches after the turbo. Can anybody that has or had one of these systems tell me what you had for initial timing? total timing? spark plugs? idle speed? and even A/F ratio at idle. I am running a retracted tip plug, cant remember what number or heat range though. Currently my biggest problem is restarts. Id like the engines to restart easily and it seems like I have to crack the throttle one click on the throttle to get them to restart when the choke is completely open.
08-07-2015 | 02:46 PM
#14
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From: Red Oak, Texas
I just bought a pair of Gentry Twin Turbos for my Scarab. I am initially going to go carbs, just because I like them and the EFI that came with them is an old speed-density system that doesn't seem all that sound. May move to EFI later on, but the "retro-rod" build design on paper lends itself to it. ANYWAYS-----the guy I bought the sets from was a turbo guy, raced, built, etc. When we discussed my idea, he said he would lock it at 32* total and never look back.
Check with Carson Brummett, he purchased the Gentry rights. SUPER great guy and knows turbos! He's been a lot of help and kind of likes simplicity in setup, particularly if carbed.
Check with Carson Brummett, he purchased the Gentry rights. SUPER great guy and knows turbos! He's been a lot of help and kind of likes simplicity in setup, particularly if carbed.
08-07-2015 | 04:42 PM
#15
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From: Pa
Ive been toying with the idea of changing the curve in my distributors. The engine is a 454, iron stock square port heads, 7.5 compression with a draw thru twin turbo system. I have a complete MSD ignition on the boat now. (billet distributors, 6AL boxes, and boost timing retard) I pull 2 degrees for every lb of boost. I am setting my boost at 10 lbs. My initial should be about 8 degrees with total a total of 36 degrees before pulling timing. I'm thinking of recurving the distributor with the lightest springs to give me more advance before boost kicks in. According to MSD directions, if I use the silver springs and the silver advance stop bushing. I should have 26 distributor degrees plus my 8 degrees if initial advance for a total of 34 degrees all in by 2100 rpm. What I am trying to do is get the engine to idle better, especially when cold.
[ATTACH=CONFIG]542751[/ATTACH][ATTACH=CONFIG]542761[/ATTACH][ATTACH=CONFIG]542762[/ATTACH][ATTACH=CONFIG]542763[/ATTACH]
[ATTACH=CONFIG]542751[/ATTACH][ATTACH=CONFIG]542761[/ATTACH][ATTACH=CONFIG]542762[/ATTACH][ATTACH=CONFIG]542763[/ATTACH]
08-08-2015 | 07:24 AM
#17
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From: On A Dirt Floor
I find it incredible that these draw thru systems start at all. For a fuel droplet, especially large one's, to make all those angles, inclines and declines, intercooler fins, turbo rotors, and etc, is just plane mind boggling...again, especially at starter cranking speeds.
08-08-2015 | 09:10 AM
#18
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From: Houston, TX, USA
My mind is slipping and I have not had a turbo motor for 15 years.
I had tried the boost retard but I do not think I had good luck with it. I did end up locking the timing so it stayed only at one spot. When you have springs advancing the timing and boost retard taking timing out there are just too many things to go wrong. I believe that is the reason I just locked it in. I want to say I had it at 28 but I was able to dial boost up to 15. I never have torn up a motor at 10 lbs of boost, wish I could say the same for 15 lbs.
It is no big deal to go and lock the timing in. Why not go and try and see what that does.
I had tried the boost retard but I do not think I had good luck with it. I did end up locking the timing so it stayed only at one spot. When you have springs advancing the timing and boost retard taking timing out there are just too many things to go wrong. I believe that is the reason I just locked it in. I want to say I had it at 28 but I was able to dial boost up to 15. I never have torn up a motor at 10 lbs of boost, wish I could say the same for 15 lbs.
It is no big deal to go and lock the timing in. Why not go and try and see what that does.
08-10-2015 | 09:42 AM
#20
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From: Fredericksburg, Va
you are not running any kind of intercoolers right ? without those I still would lock dist and run 34 and pull back to about 26 under boost, or if not boost retard try 26-28 locked. We run a blowthru set up with intercooler and are at 34 locked, no retard, but without intercoolers or E85 ???
