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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
I'm not happy with my current power output, although my car is awesome to drive and moves out well for the small-ish cam and compression.
I'm looking to make a pretty substantial move and don't want to fool with swapping a cam or heads again. I've ran the numbers on my build with a few different compression ratio options as well as cams. I'm looking for feedback on what the experts feel would be the highest SCR/DCR combo that I could pull off.
Assumptions:
1) The car will run on 93 octane, but will use C16 or Q16 for the nitrous standalone.
2) The car will see a nitrous outlet .88 jet on the weekends.
Modifications:
Balanced, blueprinted, and forged bottom end
PRC 265 heads
Ported MSD and NW102
2" Kooks to 3" catless
ATI underdrive
Halltech CF112
Lots of nitrous
How much money you got to spend on this? I do these types of big power builds quite frequently, and see sticker shock from guys who "want" more than their wallet can stand.
Assuming you have a block that will hold up to your power level goals, and the spray......
I'd look at other heads first. One set I'd consider, are the LSX heads from GM (not the DR version, but the cnc version). I really couldn't care less what anyone else thinks about these heads, they are a great, under-appreciated, reasonably priced option. I'd send them out, and have the ports/seats worked by (insert your favorite porter here). I would definitely move to a complete roller tipped system as well, and not worry about lift restrictions with the OE rockers. Lift would most likely be in the .680/.720 range..... After you get the flow bench numbers, give Mike Jones a call and have him grind you a camshaft. At your power levels, and costs you are talking about....I wouldn't even consider a shelf grind from anyone. Take the time, effort and pay for the custom profile. Jone's friggin knows his shiit and does more than just thumbing his way through Comp's lobe catalog.
It's funny how people view what is too small, to me your current cam is way bigger than what I would ever go with. I rode with a forum member with the BTR stage 4 and all I can say is that is crazy big!
I am installing my monster cam here in a couple of months, 222/234 118
before such a build --have you thought about just changing the diff to a 4:11 or a 3:90? You may be surprised. A guy with just bolt ons and a pair of cheater slicks can get in to the low 10's routinely.
I have one that me and Darin Morgan designed if intrested....
I'll need the full cam card on it to have a meaningful calculation. Definitely interested.
Originally Posted by TRSCobra
What cam are you running now? Edit: Just saw it.
And where did you hear of the BTR stage 5 cam?
It's not really a "V". It a nitrous grind he offers.
Originally Posted by Michael_D
How much money you got to spend on this? I do these types of big power builds quite frequently, and see sticker shock from guys who "want" more than their wallet can stand.
Assuming you have a block that will hold up to your power level goals, and the spray......
I'd look at other heads first. One set I'd consider, are the LSX heads from GM (not the DR version, but the cnc version). I really couldn't care less what anyone else thinks about these heads, they are a great, under-appreciated, reasonably priced option. I'd send them out, and have the ports/seats worked by (insert your favorite porter here). I would definitely move to a complete roller tipped system as well, and not worry about lift restrictions with the OE rockers. Lift would most likely be in the .680/.720 range..... After you get the flow bench numbers, give Mike Jones a call and have him grind you a camshaft. At your power levels, and costs you are talking about....I wouldn't even consider a shelf grind from anyone. Take the time, effort and pay for the custom profile. Jone's friggin knows his shiit and does more than just thumbing his way through Comp's lobe catalog.
The engine is already in the car as described above. Im going to maximize based on the components I already have with the exception of the cam.
Originally Posted by olddragger
before such a build --have you thought about just changing the diff to a 4:11 or a 3:90? You may be surprised. A guy with just bolt ons and a pair of cheater slicks can get in to the low 10's routinely.
I run 26" ET Streets at the track. On motor I run 10.70 or so as I am without nitrous. I have considered a 3.90 but for now I'll stick with the 3.42.
I'd really like to run the 249/262, but I'm worried about the low DCR. I'm not an engine guru by any means but I can't help but think, by the numbers, that the BTR IV b) and c) options would be animals. I see those being 590-615 horsepower and 520-530 ft/lbs setups on motor whereas I'm at 530 horsepower and 510 ft/lbs currently.
Id rather not add meth to the equation, but could if I had to. Preference is still 93 only.
Personally, I think the H/C combo and total horsepower should be determined by the purpose and goal of the vehicle. Horsepower is ALWAYS a means to an end, whether one admits it or not. If the goal was to run mid-9's with a 145+ trap speed, then I'd build the engine with the smallest cam possible to get the job done but use some heads that have room to grow. That's just me though.
In fact, I'd much rather just put 3.90's in the car and call it a day than to spend all that money on a solid roller setup that revs to 8K. You'll spend tons of money keeping it running too so keep that in mind. That being said, I think what Michael D said was very solid advice from what I can tell and if you were just trying to make the most peak horsepower possible, then I guess that route is a good one to take. Expensive though and in the end it might not be worth the headache.
My point? Make sure your purpose and goal is in line with the power grab. No sense in using a sledgehammer when a tack hammer will suffice.
Personally, I think the H/C combo and total horsepower should be determined by the purpose and goal of the vehicle. Horsepower is ALWAYS a means to an end, whether one admits it or not. If the goal was to run mid-9's with a 145+ trap speed, then I'd build the engine with the smallest cam possible to get the job done but use some heads that have room to grow. That's just me though.
In fact, I'd much rather just put 3.90's in the car and call it a day than to spend all that money on a solid roller setup that revs to 8K. You'll spend tons of money keeping it running too so keep that in mind. That being said, I think what Michael D said was very solid advice from what I can tell and if you were just trying to make the most peak horsepower possible, then I guess that route is a good one to take. Expensive though and in the end it might not be worth the headache.
My point? Make sure your purpose and goal is in line with the power grab. No sense in using a sledgehammer when a tack hammer will suffice.
The only money I will be spending will be for a cam, head gaskets, and milling of the heads.
All of the cams listed are hydraulic roller. I've already trapped higher than 145 as-is. Tit for tat the gearing change would also be a good move with the proposed changes. There are a few members running high 9s on motor with these cams with stock gearing and others mid-low 9s with gears.
With a 250 shot (88 pill), I would leave the 3.42 gears. Better make sure you don't rattle the motor with those cylinder pressures, or the sleeves will be toast.
What are you wanting to know about DCR? How high is too high, or how low is too low?
I wouldn't get too hung up on it, honestly. It isn't an absolute indicator of what the motor will or will not tolerate on a given octane fuel, nor is it a direct indicator of how the motor will perform. The internet world has put far too much emphasis on DCR.
DCR only factors in the SCR and when the intake valve closes...it knows nothing of the other valve events or dynamic conditions of a running engine, which obviously contribute to how the cylinder fills...not to mention the intake manifold and cylinder heads. The more you fill the cylinder, the more likely you are to run into deto, all else equal.
A lower DCR with high VE can be a problem before a higher DCR can be with a lower VE.
With those cams, I wouldn't go much over 12:1. You are getting to the point where you will have to start pulling timing around peak torque, and the tuning window shrinks. The car may perform well in spring/fall, but have issues when it gets hot in the summer. I've seen similar combination work, so it can be done...but you have to make sure that the IAT tables are setup conservatively, so it doesn't knock when it heat soaks.
I'd keep the quench as tight as possible (.035). Would be nice if Cometic would make a gasket that has a smaller bore than 4.150 as well...something like 4.130 would be ideal, as it would keep the crevice volume as low as possible.
The main difference between the BTR IV and the nitrous cam, is the nitrous cam opens the exhaust valve much earlier...which is what you want with a lot of nitrous...it helps to better clear the spent gasses. On a lower compression N/A motor, it can hurt low rpm power doing this, but with high compression and the juice, most of the work has already been done by the time the valve opens.
[QUOTE=Turbo2L;1591949361]Yes, it's the stock block.
The engine is already in the car as described above. Im going to maximize based on the components I already have with the exception of the cam.
Originally Posted by Turbo2L
The only money I will be spending will be for a cam, head gaskets, and milling of the heads.
I'm still looking foot feedback on DCR.
Sorry, I misunderstood. Thought you were starting fresh. Seeing how you are using the OE block, OE sleeves, proceed with caution. 600'ish N/A, plus spray will get you into dangerous territory real quick, and you will be replacing the block if you aren't smart about it.
With the spray, you'll want a grind with a LOT more exh duration than you would NA. The LCA and valve events get trickier too. I'd still suggest you give Jones a call to spec the cam for you. He may even want you to work those PRCs a bit, specifically the exhaust port, and open up the throat a few thou.
I don't ever worry about DCR. It's a red herring that keeps flopping around the internet. What matters, is SCR, but more importantly the DeltaP across the intake valve, how much and when it occurs.
if he changes his cam up like this wouldn't he also have to retune the exhaust? I take it he plans on running with open headers or maybe I am just too old school?
if he changes his cam up like this wouldn't he also have to retune the exhaust? I take it he plans on running with open headers or maybe I am just too old school?
It will run through 2" headers, a 3" cat less X-pipe, and then cut outs.
With a 250 shot (88 pill), I would leave the 3.42 gears. Better make sure you don't rattle the motor with those cylinder pressures, or the sleeves will be toast.
What are you wanting to know about DCR? How high is too high, or how low is too low?
I wouldn't get too hung up on it, honestly. It isn't an absolute indicator of what the motor will or will not tolerate on a given octane fuel, nor is it a direct indicator of how the motor will perform. The internet world has put far too much emphasis on DCR.
DCR only factors in the SCR and when the intake valve closes...it knows nothing of the other valve events or dynamic conditions of a running engine, which obviously contribute to how the cylinder fills...not to mention the intake manifold and cylinder heads. The more you fill the cylinder, the more likely you are to run into deto, all else equal.
A lower DCR with high VE can be a problem before a higher DCR can be with a lower VE.
With those cams, I wouldn't go much over 12:1. You are getting to the point where you will have to start pulling timing around peak torque, and the tuning window shrinks. The car may perform well in spring/fall, but have issues when it gets hot in the summer. I've seen similar combination work, so it can be done...but you have to make sure that the IAT tables are setup conservatively, so it doesn't knock when it heat soaks.
I'd keep the quench as tight as possible (.035). Would be nice if Cometic would make a gasket that has a smaller bore than 4.150 as well...something like 4.130 would be ideal, as it would keep the crevice volume as low as possible.
The main difference between the BTR IV and the nitrous cam, is the nitrous cam opens the exhaust valve much earlier...which is what you want with a lot of nitrous...it helps to better clear the spent gasses. On a lower compression N/A motor, it can hurt low rpm power doing this, but with high compression and the juice, most of the work has already been done by the time the valve opens.
Hope this helps.
Definitely good feedback. I had almost gotten too comfortable with with the stock sleeves.
hoping my Martin spec 243/259 113.5+4 ~.620".. 11.75:1.. 8.37:1.. .041 quench and same heads do well. I'm also gonna run the MSD/NW102, but 7/8" kooks.
04-06-2016, 10:24 PM
Head and Cam: Round #2
