SBE LQ4 NA Need Top End Advice
#1
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NEW to the LS World. Looking to build a SBE LQ4 NA Bracket Car. Looking for advice on heads, intake, cam, fuel system, Exhaust and Iginition. Willing to spend the money necessary to do it right the first time , just hoping to save some cash by using the stock bottom end.
Car is as follows:
1977 Cutlass, TH400 4k Stall Ultimate Converter 4.10 Gear 8.5 Rear, Car ran 12.20s with a Stock build 455 but shes getting tired and i would like to go faster.
Already have a complete steel headed LQ4 with harness waiting on me to buy the parts for it.
Any advice would be appreciated. completely at a loss with where to start on this top end.
Thanks
Car is as follows:
1977 Cutlass, TH400 4k Stall Ultimate Converter 4.10 Gear 8.5 Rear, Car ran 12.20s with a Stock build 455 but shes getting tired and i would like to go faster.
Already have a complete steel headed LQ4 with harness waiting on me to buy the parts for it.
Any advice would be appreciated. completely at a loss with where to start on this top end.
Thanks
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#4
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There isn't a real answer, everyone is going to have an opinion.
For a street car with a long runner OEM style intake manifold, I would go with the cathedral heads. They're smaller and tend to make more average power throughout a lower RPM range.
For a race car with a carb style or hi-ram intake manifold, I would go with the LS3 heads. They're bigger and tend to perform better at a higher RPM range.
The other thing to consider is that the LS3 heads start out with ~68cc chambers, which will help compression a little compared to the iron heads on there now. However, a 243 head has a 64cc chamber and the 862 heads start at 61cc. Either of which will raise compression even higher and still safe for pump gas.
For a street car with a long runner OEM style intake manifold, I would go with the cathedral heads. They're smaller and tend to make more average power throughout a lower RPM range.
For a race car with a carb style or hi-ram intake manifold, I would go with the LS3 heads. They're bigger and tend to perform better at a higher RPM range.
The other thing to consider is that the LS3 heads start out with ~68cc chambers, which will help compression a little compared to the iron heads on there now. However, a 243 head has a 64cc chamber and the 862 heads start at 61cc. Either of which will raise compression even higher and still safe for pump gas.
#6
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As far as the cam goes, you may want to talk to a sponsor. They'll want to know more about the car (gearing, trans, compression ratio, RPM range, etc) to help custom tailor a cam for your application. My guess would be something in the 23x/24x range.
#7
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OP may want to find another donor engine
Dont the early iron headed LQ4 engines have a unique and goofy crankshaft flange. Specific distance or something weird like that
Good excuse to put a stroker rotating assembly 408 together and with some stock LS3 heads make 11second power in that bigger car
Dont the early iron headed LQ4 engines have a unique and goofy crankshaft flange. Specific distance or something weird like that
Good excuse to put a stroker rotating assembly 408 together and with some stock LS3 heads make 11second power in that bigger car
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#9
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My LS-1/7 Eight Stack intake (IR) with eight 65 mm butterflies will allow the engine enough air for maximum power AND the measured runner pressure is 118 KPA (1.5lbs boost) at song. (N/A - no Turbo/SC)
Thus this IS the most powerful intake available for use on a LS engine with either a LS-1/2 or LS-7 head port.
This intake WILL require hood modification.
The average power increase is 75HP on a 346 CID, 100 HP with larger engine sizes.
I will send dyno/setup sheets to prove my above statement and a magazine article about the first 346 CID/600 HP LS engine. (11:1 with 236/242 cam)
The next item is the EMS choice, use/fit one that is easy to calibrate at the track.
My ITB kit includes the Redline ECU-882C, the same one that Robbie Shaw used the win his division championship in NHRA.
I would also suggest the use of my IGN-1A coil, the one required by NHRA for Pro-Stock.
Would you like more information ?
Lance
Thus this IS the most powerful intake available for use on a LS engine with either a LS-1/2 or LS-7 head port.
This intake WILL require hood modification.
The average power increase is 75HP on a 346 CID, 100 HP with larger engine sizes.
I will send dyno/setup sheets to prove my above statement and a magazine article about the first 346 CID/600 HP LS engine. (11:1 with 236/242 cam)
The next item is the EMS choice, use/fit one that is easy to calibrate at the track.
My ITB kit includes the Redline ECU-882C, the same one that Robbie Shaw used the win his division championship in NHRA.
I would also suggest the use of my IGN-1A coil, the one required by NHRA for Pro-Stock.
Would you like more information ?
Lance
#10
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NEW to the LS World. Looking to build a SBE LQ4 NA Bracket Car. Looking for advice on heads, intake, cam, fuel system, Exhaust and Iginition. Willing to spend the money necessary to do it right the first time , just hoping to save some cash by using the stock bottom end.
Car is as follows:
1977 Cutlass, TH400 4k Stall Ultimate Converter 4.10 Gear 8.5 Rear, Car ran 12.20s with a Stock build 455 but shes getting tired and i would like to go faster.
Already have a complete steel headed LQ4 with harness waiting on me to buy the parts for it.
Any advice would be appreciated. completely at a loss with where to start on this top end.
Thanks
![](http://i1320.photobucket.com/albums/u536/racer442olds/4284b147-ae33-4889-873b-8cb4362de088_zpspbl0jtlk.jpg)
Car is as follows:
1977 Cutlass, TH400 4k Stall Ultimate Converter 4.10 Gear 8.5 Rear, Car ran 12.20s with a Stock build 455 but shes getting tired and i would like to go faster.
Already have a complete steel headed LQ4 with harness waiting on me to buy the parts for it.
Any advice would be appreciated. completely at a loss with where to start on this top end.
Thanks
![](http://i1320.photobucket.com/albums/u536/racer442olds/4284b147-ae33-4889-873b-8cb4362de088_zpspbl0jtlk.jpg)
#12
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Few problems to camming this thing. Dished pistons and large chambers means you can't get the compression up to mid tens without milling a bunch. But the the giant 2.165" intake valve loses precious clearance
I would mill twenty. Run .040" Cometic head gaskets and an EPS 218/232 cam with a factory LS3 intake manifold
I would mill twenty. Run .040" Cometic head gaskets and an EPS 218/232 cam with a factory LS3 intake manifold
#13
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Just as a comparison...not saying the best combo, but it did OK. SBE LQ4(426whp 383wtq through a stalled auto (acceptable I guess in 98* heat w/heat index at 106*)). It has a "nitrous" cam 231/247 and milled to 65cc L92 heads. LS3 intake and NW92TB.
Last edited by ragtopz28; 12-07-2016 at 07:01 PM.
#17
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Rectangular vs. Cathedral for top end performance track only car.
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#19
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Sorry but there is a million ways to go about what you want. For me I went with 243s milled CNC titanium valves. Fast 102 rt. Thin head gasket for max compression and shooting for .030 quench, and a spec cam.