GEN III limitations
09-24-2015, 03:47 PM
#1
GEN III limitations Did a search and the consensus indicates apprx 600-650 rwhp is the limit for the Gen III non-floating rods. Of course, weight, rpm, when boost comes in etc all play a part. But, some guys are pushing BIG power - like 900+ - and some seem to be living.
Was wondering what folk's personal experience was with the Gen III motor as far as how hard the engine was pushed, length of time it lived (or still living hopefully) and what the combo/circumstances were at the time.
At this point I'm limiting my rwhp to +/-600 which I think is around 14-15psi on my 5.3. Someday I'll upgrade rods or the engine altogether.
Was wondering what folk's personal experience was with the Gen III motor as far as how hard the engine was pushed, length of time it lived (or still living hopefully) and what the combo/circumstances were at the time.
At this point I'm limiting my rwhp to +/-600 which I think is around 14-15psi on my 5.3. Someday I'll upgrade rods or the engine altogether.
09-24-2015, 04:44 PM
#2
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You'll find the answer to be all over the place depending on driving habits, if it's street driven, raced only, fuel, etc. FWIW I just bit the bullet and did rods/pistons in my ls1 and the block itself is standing up to time pretty well. This is the 4th season i've ran the motor in the car without touching it. I street drive it primarily but I don't beat on it regularly.
09-25-2015, 07:22 AM
#3
You'll find the answer to be all over the place depending on driving habits, if it's street driven, raced only, fuel, etc. FWIW I just bit the bullet and did rods/pistons in my ls1 and the block itself is standing up to time pretty well. This is the 4th season i've ran the motor in the car without touching it. I street drive it primarily but I don't beat on it regularly.
willizm, how hard were you pushing the ls1? If the #'s in your sig are the #'s you ran with it, looks like it was pushed pretty darn good.
09-25-2015, 08:50 AM
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09-25-2015, 09:06 AM
#6
Not really sure what it makes on the dyno but went to the track this past saturday and ran those times. Car weighs 3900# with me in it and had a half tank of e85. I was pushing 20psi and given the weight and mph i'm guessing i'm around 1000whp give or take.
Turbo Trans Am running at Great Lakes Dragaway GLD - YouTube
Turbo Trans Am running at Great Lakes Dragaway GLD - YouTube
So much for 650 whp limit LOL!!!!
09-25-2015, 09:29 AM
#7
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Well, let me say that it also has wisco pistons and eagle rods so it's not stock bottom end per say, but the aluminum block will take a fair amount of abuse. For how long is anyones guess. I do have a spare 2005 LQ4 in the garage as well so that will most likely be my next motor if this one gives out.
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09-25-2015, 01:34 PM
#8
Won't make enough to run a PTC, that's fo sho! 
Pretty sure I've seen a Gen3 4.8 around here that lasted awhile around 900whp... That's the route I'd go. I haven't seen the 5.3/6.0 gen3 stuff last at those levels when loaded by an actual car at the track.
Pretty sure I've seen a Gen3 4.8 around here that lasted awhile around 900whp... That's the route I'd go. I haven't seen the 5.3/6.0 gen3 stuff last at those levels when loaded by an actual car at the track.
09-25-2015, 01:51 PM
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I'm testing this question right now!
Gen III 4.8
Single China 68mm turbo, pump gas, no meth, up to 24 lbs so far and still kicking
Gen III 4.8
Single China 68mm turbo, pump gas, no meth, up to 24 lbs so far and still kicking
Last edited by Rich Halsey; 09-25-2015 at 02:33 PM.
09-25-2015, 03:26 PM
#13
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My Yank PY3400 single disk calculated at 5.4% slip right before I let off in my logs at 148mph. I'm not against PTC, but if the yank is working then i just can't justify pulling the trans to swap to a PTC at this time. 1.2 60' in a 3900lb race weight. I can't complain. Converter has always worked well with all the turbo's i've ran.
Last edited by willizm; 09-25-2015 at 04:21 PM.
09-25-2015, 08:34 PM
#14
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The only gen 3 to ever crack 4 digits on a chassis dyno was a 4.8, and there were 2 of them that did it.
The short stroke and the rod/stroke ratio on them has a lot to do with why they can handle so much.
The short stroke and the rod/stroke ratio on them has a lot to do with why they can handle so much.
09-25-2015, 08:35 PM
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My Yank PY3400 single disk calculated at 5.4% slip right before I let off in my logs at 148mph. I'm not against PTC, but if the yank is working then i just can't justify pulling the trans to swap to a PTC at this time. 1.2 60' in a 3900lb race weight. I can't complain. Converter has always worked well with all the turbo's i've ran.
09-26-2015, 06:40 AM
#16
Scat or Eagle I believe makes a replacement rod that is for a press-fit piston. Anybody know if the balance would be close enough to run as-is? Is there a problem with the pressed-pin piston in general in a high HP application?
If some folks are pushing 900whp with a Gen III perhaps is just best to leave things alone at anything below that level.
If some folks are pushing 900whp with a Gen III perhaps is just best to leave things alone at anything below that level.
09-29-2015, 07:17 AM
#17
The Gen III LQ4 has been in my car going on 3 years now. This thing has seen it's fair share of backpressure as well. I started with an on3 76mm and ran that up to 16-17 lbs. Then switched to a Turbonetics 7875 and ran that for a year or so. Currently it has a S480 92 1.10 on it now and has seen 16-17 lbs. It has seen anywhere from 600-730 rwhp, made several 9 second passes, and plenty of highway pulls. I plan on getting back to the track with it in October and turning up the boost to 18-20 lbs and seeing if it survives. It has also been on E85 since the beginning.
I drive it on the street a lot but don't beat it like it owes me money all the time. I usually just cruise around and get on it every now and again.
I drive it on the street a lot but don't beat it like it owes me money all the time. I usually just cruise around and get on it every now and again.
09-30-2015, 03:11 PM
#18
The Gen III LQ4 has been in my car going on 3 years now. This thing has seen it's fair share of backpressure as well. I started with an on3 76mm and ran that up to 16-17 lbs. Then switched to a Turbonetics 7875 and ran that for a year or so. Currently it has a S480 92 1.10 on it now and has seen 16-17 lbs. It has seen anywhere from 600-730 rwhp, made several 9 second passes, and plenty of highway pulls. I plan on getting back to the track with it in October and turning up the boost to 18-20 lbs and seeing if it survives. It has also been on E85 since the beginning.
I drive it on the street a lot but don't beat it like it owes me money all the time. I usually just cruise around and get on it every now and again.
I drive it on the street a lot but don't beat it like it owes me money all the time. I usually just cruise around and get on it every now and again.
I think some guys here put their high 4000#/5000# vehicle in the 10's with a Gen III. That is saying something!!!