PRC 2.5 243s or just CNC?
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PRC 2.5 243s or just CNC? We have a bolt-on C5 coupe that has run a best of 11.58 @ 114 with a 1.50 60'. Bolt-ons include Vararam, 1 & 7/8" ARH, Yank SS4000, 3.90, DRs, etc.
Right now we're adding a Nitrous Outlet wet kit (with Nano) and hope to spray 150 and go mid-10s. I just picked up a set of 243 heads from my tuner that already have PRC dual 0.650 springs on them and will install them along with a Tick SNS Stage III cam and hope to run 10s NA and 9s on nitrous with the stock LS6 intake and short block.
My question is whether to:
1. Put the 243 heads on stock and untouched (other than having the right springs)
2. Have TSP only do a CNC and valve job ($750)
3. Or upgrade to their 2.5 CNC/valve job where they increase the valve size ($950).
They say option #2 will pick up 30rwhp over stock 243s but I'm wondering how much #3 will add. ???
Anyone have any experience or actual dyno/track numbers?
Thanks.
Scott
Right now we're adding a Nitrous Outlet wet kit (with Nano) and hope to spray 150 and go mid-10s. I just picked up a set of 243 heads from my tuner that already have PRC dual 0.650 springs on them and will install them along with a Tick SNS Stage III cam and hope to run 10s NA and 9s on nitrous with the stock LS6 intake and short block.
My question is whether to:
1. Put the 243 heads on stock and untouched (other than having the right springs)
2. Have TSP only do a CNC and valve job ($750)
3. Or upgrade to their 2.5 CNC/valve job where they increase the valve size ($950).
They say option #2 will pick up 30rwhp over stock 243s but I'm wondering how much #3 will add. ???
Anyone have any experience or actual dyno/track numbers?
Thanks.
Scott
Take this for what its worth: I have stock 243 heads and the sns 3, my best has been a 12.5 @120 (60 foots where horrendous) I have the 1 7/8 headers, underdrive pulley and a fast 92/92. I made 427/419 with it 6 speed and stock rear end. I am a bit on the heavy side but if you want a solid 10 second pass get your heads ported and dont look back. (I regret not doing them)
Thread Starter
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Take this for what its worth: I have stock 243 heads and the sns 3, my best has been a 12.5 @120 (60 foots where horrendous) I have the 1 7/8 headers, underdrive pulley and a fast 92/92. I made 427/419 with it 6 speed and stock rear end. I am a bit on the heavy side but if you want a solid 10 second pass get your heads ported and dont look back. (I regret not doing them)
What does your car weigh and what gear?
Would you just do the porting or step up the bigger valves?
Going up to a 2.02 valve is not going to get you that much more power, while at the same time adding weight to the valvetrain. Now if you were able to get in a light 2.08 valve that might show up with a good improvement, but alas you can't go that big on your bore.
Take this for what its worth: I have stock 243 heads and the sns 3, my best has been a 12.5 @120 (60 foots where horrendous) I have the 1 7/8 headers, underdrive pulley and a fast 92/92. I made 427/419 with it 6 speed and stock rear end. I am a bit on the heavy side but if you want a solid 10 second pass get your heads ported and dont look back. (I regret not doing them)
that is true, he is in a vette and auto so I would think he could see 10's with the stock 243s. I do regret not porting the heads and that would be something to get him there with ease. on a side note there is a group of parts stockpiling to go in to put me in the 10's
Teching In
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From: Winchester,VA
For $750 and going to run Nitrous, it's a no brainer..get the port work done. If you were adding a super charger or turbo, bolt them on and go. Really at $750, I will keep this post marked and when I pick me up a set I will look them up.
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Do the porting and valve job, but keep the stock valves.
Going up to a 2.02 valve is not going to get you that much more power, while at the same time adding weight to the valvetrain. Now if you were able to get in a light 2.08 valve that might show up with a good improvement, but alas you can't go that big on your bore.
Going up to a 2.02 valve is not going to get you that much more power, while at the same time adding weight to the valvetrain. Now if you were able to get in a light 2.08 valve that might show up with a good improvement, but alas you can't go that big on your bore.
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Take this for what its worth: I have stock 243 heads and the sns 3, my best has been a 12.5 @120 (60 foots where horrendous) I have the 1 7/8 headers, underdrive pulley and a fast 92/92. I made 427/419 with it 6 speed and stock rear end. I am a bit on the heavy side but if you want a solid 10 second pass get your heads ported and dont look back. (I regret not doing them)
IMO the only reason to put larger valves into stock/ported GM castings is to
prevent the valves from being sunk(multiple valvejobs) since plenty of guys
have made 460-475 rwhp with CNC 243 castings and the 2.0"/1.55" combo.
The factory seats can only safely go 2.02 and the air still has to enter a
3.898" bore anyways.
prevent the valves from being sunk(multiple valvejobs) since plenty of guys
have made 460-475 rwhp with CNC 243 castings and the 2.0"/1.55" combo.
The factory seats can only safely go 2.02 and the air still has to enter a
3.898" bore anyways.
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Thanks guys for all of the responses. After much internet searching, making phone calls, and weighing things out I have a plan. I don't think there is necessarily "one best" way to achieve our goals and think there are several sound avenues to go.
1. We are going to send our 243s to AI for a full CNC treatment and valve job. Just going to use the stock valves since it's a small bore engine and have him check and replace the PRC springs if necessary.
2. Most likely will order a FAST 102 intake and TB from him at the same time port matched to the heads and be done with it.
3. Get a SNS Stage III cam from Martin @ Tick as well as related necessary components to change heads and cam (good head gaskets, ARP head bolts, balancer bolts, timing chain, and oil pump). Still need to research if the trunion upgrade is necessary.
I feel this should put us in the 500 rwhp NA and 600+ on a 150 shot. I think at our light race weight, provided that we hook and don't break the transmission and/or differential, that we shouldn't have an issue running 10s NA and 9s on spray.
Next issue will be a cage then ... A never ending process!
Scott
1. We are going to send our 243s to AI for a full CNC treatment and valve job. Just going to use the stock valves since it's a small bore engine and have him check and replace the PRC springs if necessary.
2. Most likely will order a FAST 102 intake and TB from him at the same time port matched to the heads and be done with it.
3. Get a SNS Stage III cam from Martin @ Tick as well as related necessary components to change heads and cam (good head gaskets, ARP head bolts, balancer bolts, timing chain, and oil pump). Still need to research if the trunion upgrade is necessary.
I feel this should put us in the 500 rwhp NA and 600+ on a 150 shot. I think at our light race weight, provided that we hook and don't break the transmission and/or differential, that we shouldn't have an issue running 10s NA and 9s on spray.
Next issue will be a cage then ... A never ending process!
Scott
The trunion upgrade should be done. Its more piece of mind than anything. I would hate to have the heart sinking feeling when you find bearing needles in your oil pan. Your game plan sounds like it should get you to your goals with no problem. Unfortunately you will break things in the driveline.... ask my driveshaft/rearend/pocketbook
Do it all now. If you don't you will regret it later. I went with TEA 243 and I'm happy I went with stage 2.
You have a good running car. I actually want a c5. Any weight reduction? Yeah the cage issue lol that's where I'm at.
You have a good running car. I actually want a c5. Any weight reduction? Yeah the cage issue lol that's where I'm at.
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TECH Apprentice
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The 11.58 bolt-on was in fluke air: -2000' DA but we were still pretty happy running that with the OEM LS1.
