Is 475-500 rwhp NA possible with an LT4 intake?
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Joined: Oct 2002
Posts: 6,518
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by WS6 TA
Is it possible? Sure. Is it likely? Not unless you know more then 99% of people on this board and/or have more money to spend on it then most of us. Of course, why not take the easy way out and go mechanical roller?
Some quick numbers to play with:
To be safe 475rwhp = ~570bhp
At 100% VE a 350 will have to be spinning about 7500rpm to do it (figure, for most people’s setups this could be lightly optimistic and you might have to turn a few hundred more rpm)
You’ll need over 275cfm intake port flow at at least 20% under your peak lift
You’ll need a cam that will give you peak hp around 7500rpm and a valve train that will be reliable to 8K
At that point, to get a HR setup to live you’re talking about using every trick in the book, light valves, retainers…, rev kit, trick valve springs… you’re at the point that it will be difficult to do it without heads that will require offset rockers…
All of this gets much easier/cheaper if you just suck it up and live with adjusting valve lash once in a while. OTOH, you won’t save money on the short block unless you spend the $$$ for a bigger displacement so you don’t have to wind it up as tight, but even something like a 396 will want >6750rpm to get into this range.
Some quick numbers to play with:
To be safe 475rwhp = ~570bhp
At 100% VE a 350 will have to be spinning about 7500rpm to do it (figure, for most people’s setups this could be lightly optimistic and you might have to turn a few hundred more rpm)
You’ll need over 275cfm intake port flow at at least 20% under your peak lift
You’ll need a cam that will give you peak hp around 7500rpm and a valve train that will be reliable to 8K
At that point, to get a HR setup to live you’re talking about using every trick in the book, light valves, retainers…, rev kit, trick valve springs… you’re at the point that it will be difficult to do it without heads that will require offset rockers…
All of this gets much easier/cheaper if you just suck it up and live with adjusting valve lash once in a while. OTOH, you won’t save money on the short block unless you spend the $$$ for a bigger displacement so you don’t have to wind it up as tight, but even something like a 396 will want >6750rpm to get into this range.
I don't agree that a 350-360 or so cube motor needs 7500rpm to get 570-600hp, i've seen it done with 6200-6500rpm and with hyd rollers. 290cfm @ .550 ports are all you really need to get it done, cams in the 230-240 duration range and Ti retainers with strong enough dual springs to control the valves. True hollow stem valves and beehive springs might help the RPM range but you don't need that RPM to get that kind of power.
When you have less head than that say, 265-270cfm, more cubes and more cam are needed, so a good solid roller helps.
Cookie Cutter Recipe for a 600hp Hyd Roller Small Block
My view on hyd rollers is that people don't understand the way that system works so they can't optimize it to turn 7,000rpm or more. It doesn't take much you just have to understand that the system is just that a system.
Bret
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Joined: Feb 2003
Posts: 2,639
From: Mooresville, NC
Re: Is 475-500 rwhp NA possible with an LT4 intake?
thats just awesome...
a quote from joe in the link above...hard to imagine that achieving 675 hp
"So, I'll run a cam with about .590-inch lift with about 236 degrees at .050. I want the engine to peak between 6,300-6,400 rpm, and I'll play with the combination until I get it the way I want it."
a quote from joe in the link above...hard to imagine that achieving 675 hp
"So, I'll run a cam with about .590-inch lift with about 236 degrees at .050. I want the engine to peak between 6,300-6,400 rpm, and I'll play with the combination until I get it the way I want it."
Banned
Joined: Oct 2002
Posts: 6,518
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by marshall93z
thats just awesome...
a quote from joe in the link above...hard to imagine that achieving 675 hp
"So, I'll run a cam with about .590-inch lift with about 236 degrees at .050. I want the engine to peak between 6,300-6,400 rpm, and I'll play with the combination until I get it the way I want it."
a quote from joe in the link above...hard to imagine that achieving 675 hp
"So, I'll run a cam with about .590-inch lift with about 236 degrees at .050. I want the engine to peak between 6,300-6,400 rpm, and I'll play with the combination until I get it the way I want it."
One thing he does extremely well is build motors the right way for cheap. Good pistons, good heads, right cam, good machine work and doesn't spend stupid money on expensive cranks and rods. A good quote from him "we used to spin stock rods to 8,000rpm and I've never had one fail. These guys now that buy stupid expensive forged and billet rods for 400hp circle track motors kill me."
BTW the cam he had in that motor was a 234/234 .560/.560 108 LSA, he also had 215RR heads and a single plane.
Bret
Thread Starter
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Joined: Nov 2001
Posts: 648
From: Richardson, TX USA
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Back to the subject.
Bret,
Am I going to make 500 to the wheels. I need to talk to you about the valvetrain parts we talked about. Larry has the intake and heads, to see what he can come up with. I am going out of town on Thursaday for 10 days.
Michael Kelly
Bret,
Am I going to make 500 to the wheels. I need to talk to you about the valvetrain parts we talked about. Larry has the intake and heads, to see what he can come up with. I am going out of town on Thursaday for 10 days.
Michael Kelly
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Joined: Jul 2001
Posts: 752
From: Double Oak TX
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by SStrokerAce
I've sat down and talked with Joe. He is a nice old guy who knows his ****...
One thing he does extremely well is build motors the right way for cheap. Good pistons, good heads, right cam, good machine work and doesn't spend stupid money on expensive cranks and rods. A good quote from him "we used to spin stock rods to 8,000rpm and I've never had one fail. These guys now that buy stupid expensive forged and billet rods for 400hp circle track motors kill me."
BTW the cam he had in that motor was a 234/234 .560/.560 108 LSA, he also had 215RR heads and a single plane.
Bret
One thing he does extremely well is build motors the right way for cheap. Good pistons, good heads, right cam, good machine work and doesn't spend stupid money on expensive cranks and rods. A good quote from him "we used to spin stock rods to 8,000rpm and I've never had one fail. These guys now that buy stupid expensive forged and billet rods for 400hp circle track motors kill me."
BTW the cam he had in that motor was a 234/234 .560/.560 108 LSA, he also had 215RR heads and a single plane.
Bret
Now what I find important is attention to detail, common sense, high standards and years of trial and error experience. Trust me... I learned this the hard way.
Pretty easy to negate the performance of a $5k rotating assembly with just the wrong cylinder hone. Give me a $2k or less assembly and the right person putting everything together any day. Pay them the little extra instead and get a lot!
The difference between wisdom and intelligence is experience.
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Joined: Jan 2000
Posts: 202
From: Lincoln, CA
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Wow, I feel like the little kid sitting around the fire listening to all the adults... Great info here.
I'll throw in my own experience.
I pulled 467 rwhp (safely on 91 octane) with an LT1 intake manifold. 480 rwhp somewhat on the edge of safety, for a "street" motor.
396, solid roller, AFR 190's worked to 218 range ($4,080 in my COMPLETE top end, shipping, porting, flow benching, springs, retainers, pushrods, lifters, etc, etc.)
Made peak HP from 6,100-6,900 (with the stock PCM, it won't rev past 6,996 rpm.)
The intake is port matched to the AFR heads, and the monoblade TB on the front is matched to the intake opening as well.
I'm freshening up this motor, and thinking about stepping down to a BBK 58mm, but not sure if I will loose any power. 5-10 hp isn't bad for the benifits of a stock TB I will gain back.
I'll throw in my own experience.
I pulled 467 rwhp (safely on 91 octane) with an LT1 intake manifold. 480 rwhp somewhat on the edge of safety, for a "street" motor.
396, solid roller, AFR 190's worked to 218 range ($4,080 in my COMPLETE top end, shipping, porting, flow benching, springs, retainers, pushrods, lifters, etc, etc.)
Made peak HP from 6,100-6,900 (with the stock PCM, it won't rev past 6,996 rpm.)
The intake is port matched to the AFR heads, and the monoblade TB on the front is matched to the intake opening as well.
I'm freshening up this motor, and thinking about stepping down to a BBK 58mm, but not sure if I will loose any power. 5-10 hp isn't bad for the benifits of a stock TB I will gain back.
Registered User
Joined: Jan 2000
Posts: 202
From: Lincoln, CA
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by marshall93z
i believe i would have went with something bigger than 190's...
Shoot, even my stock Z06 is guttless under 3,500 rpm.
We chose to start with the 190's for the capability of keeping the low lift flow numbers good.
I'm considering selling these heads, and stepping up to 220's or 227's now. I'm buying a car trailer so I can trailer the car now. I don't particularly like driving the car on the street anymore... 26" tall tires, with 4.30 gears, and EVERY suspension piece heim jointed has turned into no fun. So now drivability can take a backseat, and go for max HP.
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Joined: Jul 2001
Posts: 752
From: Double Oak TX
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by Black95Form
What is prompting you to move from a monoblade to a 58mm?? Please tell.
Michael
Michael
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Joined: Jan 2000
Posts: 202
From: Lincoln, CA
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by Denny McLain
Not sure what prompting WHYTLIE, but the throttle responce is a bit trick for everyday driving on the one I had. Gets a lot of air real quick in my opinion and I'm still wondering at what hp level you really need one.
'97 M3 5-spd (wife's car)
'72 Corvette 454 4-spd (my dad's old car, mine now)
'02 Z06 (6-spd of course)
'96 Z-28 6-spd
The throttle is very different in all the cars as well as the clutches.
But if my math is right, 6900 rpm x 396 = 2732400 / 3468 = 787.88 cfm is needed. I believe the AS&M monoblade is 1300 cfm capable.
I think a BBK 52mm is limited to 740 cfm, not sure about their 58mm TB, but probably 900 cfm.
The only thing I do like about the monoblade is that it is all open for my nitrous/fuel to go in nice and easy with no divider.
But the IAC circuits have me wondering. That has always been the restriction for driveability and tuning.
I'm still doing research and debating these thoughts with people smarter then myself (or at least more experienced.)
Registered User
Joined: Jul 2001
Posts: 752
From: Double Oak TX
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by WHYTLIE
Exactly. My throttle response is a bit tricky, but jumping between the 5 cars I drive makes it all tricky. Biggest difference is the shift configuration and clutch release points.
'97 M3 5-spd (wife's car)
'72 Corvette 454 4-spd (my dad's old car, mine now)
'02 Z06 (6-spd of course)
'96 Z-28 6-spd
The throttle is very different in all the cars as well as the clutches.
But if my math is right, 6900 rpm x 396 = 2732400 / 3468 = 787.88 cfm is needed. I believe the AS&M monoblade is 1300 cfm capable.
I think a BBK 52mm is limited to 740 cfm, not sure about their 58mm TB, but probably 900 cfm.
The only thing I do like about the monoblade is that it is all open for my nitrous/fuel to go in nice and easy with no divider.
But the IAC circuits have me wondering. That has always been the restriction for driveability and tuning.
I'm still doing research and debating these thoughts with people smarter then myself (or at least more experienced.)
'97 M3 5-spd (wife's car)
'72 Corvette 454 4-spd (my dad's old car, mine now)
'02 Z06 (6-spd of course)
'96 Z-28 6-spd
The throttle is very different in all the cars as well as the clutches.
But if my math is right, 6900 rpm x 396 = 2732400 / 3468 = 787.88 cfm is needed. I believe the AS&M monoblade is 1300 cfm capable.
I think a BBK 52mm is limited to 740 cfm, not sure about their 58mm TB, but probably 900 cfm.
The only thing I do like about the monoblade is that it is all open for my nitrous/fuel to go in nice and easy with no divider.
But the IAC circuits have me wondering. That has always been the restriction for driveability and tuning.
I'm still doing research and debating these thoughts with people smarter then myself (or at least more experienced.)
Registered User
Joined: Jan 2000
Posts: 202
From: Lincoln, CA
Re: Is 475-500 rwhp NA possible with an LT4 intake?
Originally Posted by Denny McLain
Being part of the Pepsi generation I could be wrong.... but if my memory is correct, isn't the 58mm tb 1050?
Possibly, I haven't actually looked up the numbers in a long time.
I sorta grabbed that number out of the air. Another guy I was talking to claimed the BBK 52mm was 725 or 750 cfm.
But the monoblade is 1300, right?
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