Lq9 build
Teching In
Joined: Sep 2022
Posts: 26
Likes: 1
I'm in the same boat. Ive been mulling over this for as long as I've bought this lq9. Same combo, diff vehicle. This whole dcr thing was new to me. I'm old school, so we always based on static number.
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
Staging Lane
Joined: Aug 2020
Posts: 94
Likes: 10
I'm in the same boat. Ive been mulling over this for as long as I've bought this lq9. Same combo, diff vehicle. This whole dcr thing was new to me. I'm old school, so we always based on static number.
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
Everything I read. Says a dcr of 8.5:1 is ok for pump gas.
Joined: Jul 2007
Posts: 1,502
Likes: 177
From: ELSA, South TEXAS (956) 802-7700
Just throw on some LS3 heads milled .015, Cometic .040 and you'll be at around 11:1 cr. Rectangle Ports performance for price can't be beat, especially when you consider LS3 Intake price as well. Then throw in a TSP Stage 3 231-246 Cam with a 3600 stall and you'll be happy on a budget.
I'm in the same boat. Ive been mulling over this for as long as I've bought this lq9. Same combo, diff vehicle. This whole dcr thing was new to me. I'm old school, so we always based on static number.
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
But, my combo is at roughly 8.7 with the same .048 gaskets, lq9, 799 heads, and that ghost cam. It does have a late ABDC at 43* @.50. At seat to seat its 67. Which is a pretty good number. I was debating to just use my old BTR stage 2 cam as it was 69. And it would lower the dcr even more.
But, from what I've been reading, ~8.5-9.1 seems to be ok with 91/93. Apparently if the quench is good, and your dynamic compression is less than 200psi, then we should be ok??!?
At least I hope so. @Phobos84 comment about having to run e85 isnt very convincing though
Just throw on some LS3 heads milled .015, Cometic .040 and you'll be at around 11:1 cr. Rectangle Ports performance for price can't be beat, especially when you consider LS3 Intake price as well. Then throw in a TSP Stage 3 231-246 Cam with a 3600 stall and you'll be happy on a budget.
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,233
Likes: 1,523
From: Ohio, Georgia, Nevada, Texas
Good discussion going here, folks!
There are some things we wanted to point out. ALWAYS calculate dynamic compression at Advertised/.006" for the IVC. Don't take general octane to compression guidelines as go/no go gauges. One combo at 8:1 dynamic could knock and one at 9.2:1+ may not knock at all. It's all in the combo. Things like the weight of the vehicle, fuel, octane, converter, drivetrain, altitude, etc.
There are some things we wanted to point out. ALWAYS calculate dynamic compression at Advertised/.006" for the IVC. Don't take general octane to compression guidelines as go/no go gauges. One combo at 8:1 dynamic could knock and one at 9.2:1+ may not knock at all. It's all in the combo. Things like the weight of the vehicle, fuel, octane, converter, drivetrain, altitude, etc.
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TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
Good discussion going here, folks!
There are some things we wanted to point out. ALWAYS calculate dynamic compression at Advertised/.006" for the IVC. Don't take general octane to compression guidelines as go/no go gauges. One combo at 8:1 dynamic could knock and one at 9.2:1+ may not knock at all. It's all in the combo. Things like the weight of the vehicle, fuel, octane, converter, drivetrain, altitude, etc.
There are some things we wanted to point out. ALWAYS calculate dynamic compression at Advertised/.006" for the IVC. Don't take general octane to compression guidelines as go/no go gauges. One combo at 8:1 dynamic could knock and one at 9.2:1+ may not knock at all. It's all in the combo. Things like the weight of the vehicle, fuel, octane, converter, drivetrain, altitude, etc.
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
Staging Lane
Joined: Aug 2020
Posts: 94
Likes: 10
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
@Summitracing I finally have all the parts gathered up to put the LQ9 back together, I did go with the 8715R1 cam and all the other parts we discussed earlier.... 862 heads, flat top lq9 pistions with new rings, bearings, felpro gaskets ect....
Now I'm considering whether I should upgrade the converter while I have it apart. What do you think of the SUM-700335 converter? It says 2800-3200 stall. My car has 3.55 gears and 27" tires.
Will this be good for a street/cruiser setup? Thanks
Now I'm considering whether I should upgrade the converter while I have it apart. What do you think of the SUM-700335 converter? It says 2800-3200 stall. My car has 3.55 gears and 27" tires.
Will this be good for a street/cruiser setup? Thanks
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,233
Likes: 1,523
From: Ohio, Georgia, Nevada, Texas
@mmm88ta,
Thank you for your patronage! We understand it takes time to gather parts up and get builds put together.
Onto a converter for the LQ9 with our 8715R1 in your 1970 Pontiac Tempest. Technically, a converter wouldn't be required here. However, getting a stall converter that's matched well to the combo will help get everything out of it. Our SUM-700335 converter would be a good fit for this combo if you planned on staying NA. If a power adder is in the cards we'd recommend upgrading to our SUM-700340 Pro LS series converter. That is furnace-brazed and has an anti-ballooning plate.
When going to a stall converter it's recommended to get an auxiliary transmission cooler. By design, a higher stall converter creates slippage which creates heat. This is potentially damaging to a transmission. This is where an auxiliary cooler comes in. It will help extend the life of your transmission and give you that peace of mind.
Thank you for your patronage! We understand it takes time to gather parts up and get builds put together.
Onto a converter for the LQ9 with our 8715R1 in your 1970 Pontiac Tempest. Technically, a converter wouldn't be required here. However, getting a stall converter that's matched well to the combo will help get everything out of it. Our SUM-700335 converter would be a good fit for this combo if you planned on staying NA. If a power adder is in the cards we'd recommend upgrading to our SUM-700340 Pro LS series converter. That is furnace-brazed and has an anti-ballooning plate.
When going to a stall converter it's recommended to get an auxiliary transmission cooler. By design, a higher stall converter creates slippage which creates heat. This is potentially damaging to a transmission. This is where an auxiliary cooler comes in. It will help extend the life of your transmission and give you that peace of mind.
@Summitracing Thanks for the info. I'm excited to get the car on the road with the new powerplant. Will a converter make a big difference or should I wait until I add a turbo or something in the future. I'd rather buy a $700 converter than a $500 now and $700 later but if it's not a huge difference while I'm still NA I will hold off.
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,233
Likes: 1,523
From: Ohio, Georgia, Nevada, Texas
@mmm88ta,
A converter will make a big difference. It's not uncommon for folks with stock F-bodies or trucks to put a stall converter in. A stall converter by itself can help off-line performance, 60 ft times, and ET. Even if you're not racing this at the strip a correctly matched stall converter will help get you moving at peak torque. A look into this article will shed light on this. There are some good takeaways on why you want a stall converter and that the car will still move under the stall speed of the converter. There is some in-the-weeds talk about 6,000 rpm converters but that still adds value to why you'd want a stall converter.
With that being said we'd go with our SUM-700340 Pro series converter for this combo. It's going to help get everything out of the current combo. If you change it up in the future and go with a power adder it'll be ready for it.
A converter will make a big difference. It's not uncommon for folks with stock F-bodies or trucks to put a stall converter in. A stall converter by itself can help off-line performance, 60 ft times, and ET. Even if you're not racing this at the strip a correctly matched stall converter will help get you moving at peak torque. A look into this article will shed light on this. There are some good takeaways on why you want a stall converter and that the car will still move under the stall speed of the converter. There is some in-the-weeds talk about 6,000 rpm converters but that still adds value to why you'd want a stall converter.
With that being said we'd go with our SUM-700340 Pro series converter for this combo. It's going to help get everything out of the current combo. If you change it up in the future and go with a power adder it'll be ready for it.
Right now the car is just a fun cruiser to beat on on the street and hit cruise nights with the kids. I don't daily it as much as I used to but it still gets driven very often.