ls7 with ls3 top end
10-04-2013, 08:57 PM
#1
ls7 with ls3 top end Anyone done this? I'm looking to get reliability out of my ls7 with all these valve guides issues going around. Do they bolt right in without modifications or do they need to be reworked? Most likely custom length pushrod length but what about rockers, stock ls3? Most likely performance will be lost n/a bit I plan on adding boost. All help is appreciated
10-04-2013, 09:52 PM
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Anyone done this? I'm looking to get reliability out of my ls7 with all these valve guides issues going around. Do they bolt right in without modifications or do they need to be reworked? Most likely custom length pushrod length but what about rockers, stock ls3? Most likely performance will be lost n/a bit I plan on adding boost. All help is appreciated
I just switched over to ported LS 7 heads and a ported LS 7 intake. It appeared I made more power above 4500 rpm, but lost hp/torque under 4500 rpm. But waiting now for a better dyno day as when I dynoed it was very high on humidity/temp and they couldn't get the right factors set in.
On GM performance, they used LS 3 heads on a LS 7 short block, then bolted on a LS 9 supercharger and made over 800 at the crank. The LS 3 heads can use 1 3/4 inch headers, the LS 7 heads ported can use 1 3/4 but the its better with 1 7/8 inch.
10-04-2013, 10:24 PM
#4
I did this. I used a new LS 7 short block RTA with Callies crank, comp star rods and wiseco pistons. Made 550 rwhp and 510 rwtq on a 239/251 cam using LS 3 heads and ls3 intake/ ls3 rockers.
I just switched over to ported LS 7 heads and a ported LS 7 intake. It appeared I made more power above 4500 rpm, but lost hp/torque under 4500 rpm. But waiting now for a better dyno day as when I dynoed it was very high on humidity/temp and they couldn't get the right factors set in.
On GM performance, they used LS 3 heads on a LS 7 short block, then bolted on a LS 9 supercharger and made over 800 at the crank. The LS 3 heads can use 1 3/4 inch headers, the LS 7 heads ported can use 1 3/4 but the its better with 1 7/8 inch.
I just switched over to ported LS 7 heads and a ported LS 7 intake. It appeared I made more power above 4500 rpm, but lost hp/torque under 4500 rpm. But waiting now for a better dyno day as when I dynoed it was very high on humidity/temp and they couldn't get the right factors set in.
On GM performance, they used LS 3 heads on a LS 7 short block, then bolted on a LS 9 supercharger and made over 800 at the crank. The LS 3 heads can use 1 3/4 inch headers, the LS 7 heads ported can use 1 3/4 but the its better with 1 7/8 inch.
Did you use ls7 head gaskets? What about pushrods?
10-04-2013, 10:31 PM
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Yes, LS 7 lifters work. LS 7 head gaskets along with all the accessories off my LS 6. Wiring harnesses for the sensors and MAP. LS 7 MAP is front and same on the LS 3. Remember LS 3 fuel rail is different than LS 7 fuel rail. Had to relocate knock senors. Spliced the map wiring as it was in the rear on my LS 6 manifold. Injectors are the same LS7/LS3. Yes, different push rod lengths for the LS 3 and the LS 7.
Call maybe some of the vendors or Texas Speed and ask for John, he was a big help and has done this before.
Call maybe some of the vendors or Texas Speed and ask for John, he was a big help and has done this before.
Last edited by Skypilot797; 10-04-2013 at 10:48 PM.