My somewhat coherent thread on the topic of street/strip turbo LS combinations.
08-25-2012, 11:56 AM
#82
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Front mount vs. Rear mount I'm not new to Ls1Tech, but I've never posted before. Love the forum.
I'm building a mid-engine car. I have an LQ4 from my crew cab that my wife totaled, It only had 50K on it. I'm interested in using Twin turbo's and wouldn't mind the 900+ Hp range. This may be too much for a stock block. Honestly I would be more interested in beast power over a wide band than Max Hp.
#1
The clearance on the front of the engine will be very tight. The intake (an LS6) will be flipped. So if I understand correctly the rear mount would serve my purpose.
#2
At this point I plan with staying with the 317's and replace the pistons with flat tops. If it needs some block work it will be done.
#3
This will be more of a track car but street driven. The trans-axle will have 6 gears that will pobably be spread a bit.
Being new to turbo's I could use some help. Any imput would be appreciated.
I'm building a mid-engine car. I have an LQ4 from my crew cab that my wife totaled, It only had 50K on it. I'm interested in using Twin turbo's and wouldn't mind the 900+ Hp range. This may be too much for a stock block. Honestly I would be more interested in beast power over a wide band than Max Hp.
#1
The clearance on the front of the engine will be very tight. The intake (an LS6) will be flipped. So if I understand correctly the rear mount would serve my purpose.
#2
At this point I plan with staying with the 317's and replace the pistons with flat tops. If it needs some block work it will be done.
#3
This will be more of a track car but street driven. The trans-axle will have 6 gears that will pobably be spread a bit.
Being new to turbo's I could use some help. Any imput would be appreciated.
08-25-2012, 04:08 PM
#86
Launching!
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I just finished my first ls turbo build.
I did a stock 6.0 with a 234/230 on 116 cam with a gt 4276 T4 1.15 housing. It spools really good on a PTC stalled 4l80e and did 767hp on 15.5 psi I stopped at 6500 on the pull since its a stock bottom end car. The HP was still climbing at that point as well. I am not even in the sweet spot of the pressure ratio yet and it should have a bit more in it.
the car is 80% street and 20% drag/autocross and besides twins turbos, i dont think i would go much bigger, maybe a 80mm compressor in a BW series.
I did a stock 6.0 with a 234/230 on 116 cam with a gt 4276 T4 1.15 housing. It spools really good on a PTC stalled 4l80e and did 767hp on 15.5 psi I stopped at 6500 on the pull since its a stock bottom end car. The HP was still climbing at that point as well. I am not even in the sweet spot of the pressure ratio yet and it should have a bit more in it.
the car is 80% street and 20% drag/autocross and besides twins turbos, i dont think i would go much bigger, maybe a 80mm compressor in a BW series.
08-25-2012, 07:44 PM
#87
I'm a firm believer in my reverse split cam. Sold it at one point. Installed a smaller, 228ish even pattern cam. Car was noticeably slower, and spooled slower too. After a year or two with it in the car.... I tracked down the reverse split cam I sold and the owner still had it sitting in the box I shipped it in 
Bought it back, reinstalled it, and the car then hauled *** on the top end again.
A couple local tuners thought I was an idiot for thinking going to a smaller cam would be faster.... And they laughed when I reinstalled the reverse big stick and picked up hp. "Duh" they said.
Bought it back, reinstalled it, and the car then hauled *** on the top end again. A couple local tuners thought I was an idiot for thinking going to a smaller cam would be faster.... And they laughed when I reinstalled the reverse big stick and picked up hp. "Duh" they said.
What was the LSA and installed centerline of the 228/228 cam? What lobes?
No offense but a generic statement saying I went from this cam to that cam doesn't tell the picture as a whole. Need to know a little more information than that
This info would include, but not be limited to:
SCR
Engine size
Turbo size including AR and turbine size
Intake manifold used
Cylinder heads
RPM shifts will occur
There are more, but this are more valuable in the short term when comparing two camshafts.
08-25-2012, 07:49 PM
#88
I really like the LS9 cam in a mild set-up.
Put on some lobes I frequently use you have a very nice docile cam on your hands.
I believe Slowhawk has already done this with results in the 900rwhp+ range.
Maybe he will share more details with us.
08-26-2012, 02:14 AM
#89
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I'm about to finish my fuel system for the e85.
Build consists of
5.3 Lm7
Ls9 cam
80lb injectors, double pumper, Fuel regulator.
3600 stall
Gt45 turbo.
Hopefully I can get my 3900lb gto into the 10s once again.
Here are the specs for the gt45
Exhaust :inducer 87.4mm exducer: 77mm
Compressor: 68.7mm exducer: 97.8
1.05 ar .
What whp do you guys think this will support on a 5.3?
Last edited by a4ls2goat; 08-26-2012 at 02:22 AM.
08-26-2012, 10:56 AM
#90
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with a set of twins on, for example, a heads/cam 346 is the transient response with an M6 car negated when going to a stalled auto? would it be pointless to limit yourself on the top end with a set of smaller turbos when the bottom end doesnt matter because of a ~3000 rpm stall?
08-26-2012, 11:08 AM
#91
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Once again it seems as though many people are underestimating holsets. My personal experience with holsets and Garrett (journal) bearing seem to point out holsets superiority when matched with similar garrett variants. Not to mention there is quite an aftermarket following of holset as they are OEM in many diesel applications. I would take a pair of externally gated he351cw's over gt35's any day with a sub 383ci forged engine.
Another thing I haven't really seen discussed much when talking arout factory shortblock engines, is the amount of time the combustion event has to transfer stress onto the rotating assembly, specifically the rods.
I have encountered this problem when dealing with riced out 4-cyl. Running a larger, laggier turbo paired with tuning out some power down low allowed us to make more whp in the top end.. sometimes even 100+whp more (max hp) before rods were making their exit. The rods weren't subjected to the violent onset of a quick spooling turbo. With my current build, I am eager to see the results of a larger, laggier twin set and pulling out timing (relatively) before peak torque is made...
Not saying ill be able to do it, but I am willing to bet someone will put down 1000+whp with a stock shortblock 4.8/5.3 set up
Another thing I haven't really seen discussed much when talking arout factory shortblock engines, is the amount of time the combustion event has to transfer stress onto the rotating assembly, specifically the rods.
I have encountered this problem when dealing with riced out 4-cyl. Running a larger, laggier turbo paired with tuning out some power down low allowed us to make more whp in the top end.. sometimes even 100+whp more (max hp) before rods were making their exit. The rods weren't subjected to the violent onset of a quick spooling turbo. With my current build, I am eager to see the results of a larger, laggier twin set and pulling out timing (relatively) before peak torque is made...
Not saying ill be able to do it, but I am willing to bet someone will put down 1000+whp with a stock shortblock 4.8/5.3 set up
08-26-2012, 02:40 PM
#93
7675 on the lq9 it ran 15psi
7675 on the 5.3 it ran 22psi. my waste gate is not in the best location and i could not get boost any lower with the 5.3l
im going to have to say it was due to the loss of displacement.
i raised the rpm and boost leaving off the t brake from the lq9 and it just couldn't launch, it would hit and bog right after the hit. then it would start building boost and flat line around 12 psi in 1st gear, then hit 2nd and it would jump straight to 22psi the rest of the pass.
08-26-2012, 09:41 PM
#94
with the tc78 it was running 12psi on the lq9
7675 on the lq9 it ran 15psi
7675 on the 5.3 it ran 22psi. my waste gate is not in the best location and i could not get boost any lower with the 5.3l
im going to have to say it was due to the loss of displacement.
i raised the rpm and boost leaving off the t brake from the lq9 and it just couldn't launch, it would hit and bog right after the hit. then it would start building boost and flat line around 12 psi in 1st gear, then hit 2nd and it would jump straight to 22psi the rest of the pass.
7675 on the lq9 it ran 15psi
7675 on the 5.3 it ran 22psi. my waste gate is not in the best location and i could not get boost any lower with the 5.3l
im going to have to say it was due to the loss of displacement.
i raised the rpm and boost leaving off the t brake from the lq9 and it just couldn't launch, it would hit and bog right after the hit. then it would start building boost and flat line around 12 psi in 1st gear, then hit 2nd and it would jump straight to 22psi the rest of the pass.
To the guy that asked what his combo should make with the turbo he chose I would say 750rwhp on high boost through an auto. Enough to pound the bearings out of that stock Lm7
08-30-2012, 05:31 PM
#95
08-30-2012, 05:45 PM
#97
08-30-2012, 08:47 PM
#98
there was no damage to any of the fins after the lq9 died and if there was something that wrong would it still spool very quickly and make 22psi? say if the bearing where going out? im not sure so i am really just asking?
i was always disappointed in the 5.3l never seemed like it lived up to everyones hipe.
08-30-2012, 09:03 PM
#99
it had the exact same setup that the lq9 did. but i was also thinking how pathetic the 5.3l was.
there was no damage to any of the fins after the lq9 died and if there was something that wrong would it still spool very quickly and make 22psi? say if the bearing where going out? im not sure so i am really just asking?
i was always disappointed in the 5.3l never seemed like it lived up to everyones hipe.
there was no damage to any of the fins after the lq9 died and if there was something that wrong would it still spool very quickly and make 22psi? say if the bearing where going out? im not sure so i am really just asking?
i was always disappointed in the 5.3l never seemed like it lived up to everyones hipe.