What do I need for 600+rwhp?

Gearbanger 101 · Apr 29, 2005

Orr89rocz said:
unless its a turbo...

blowers are run off the crank pulley so are constantly stuffing air into the motor, at all rpms.

Incorrect....Let me school you a little on superchargers and turbo’s. Blowers aren't always stuffing air into the engine. At least the modern kits now a days aren’t. Sure the old school 671-roots blowers were always compressing air and cramming it into the motor, but neither the Kenne Bell or latest generation of Roots blowers or most Centrifugals for that matter work that way anymore. They now incorporate a bypass valve in the system to relieve unwanted/unneeded manifold pressure throughout. A positive Displacement blower (since that it what you’re comparing it to) is only running in a boosted state, when you want them to. The harder you push the pedal to the floor, the more eager the boost gauge will climb. But if one chose to do so, the could run their blown car all the way up to redline without even coming out of vacuum. All it takes is a little moderation with the accelerator pedal. While running in a non-boosted state, positive displacement blower have been shown to use no more than 1/3 of a horsepower to spin the pulley. Not exactly the power drain you’d hoped for, huh

Turbo's on the other hand regardless of their size will experience a measurable amount of boost lag until exhaust pressure has built sufficiently. Turbo’s have also come a long way in comparison to the ones available in the 4-pots of the ‘80’s and the lag experienced can be minimized with gearing and proper sizing for the application, but it is still a factor that can not be eliminated completely…..especially where building one to support 600rwhp is concerned. Much like a centrifugal supercharger, you do not get the instantaneous throttle response and off idle torque with a turbo you get with a positive displacement blower. Power output is bases on exhaust pressure that must be built with engine RPM. That is why in drag racing you often hear of turbo cars “loading up” on the bottom end to compensate for this. Which does improve low end performance, but it a major PITA to try to accomplish on a street car. So must just live with the lag because of the plentiful power they make up top.

So there….now you know.

Orr89rocz · Apr 30, 2005

thanks for the info, but still, i believe its more streetable for turbo as i havent seen any super high horsepower cars running blowers, that are streetable

most KB hp i was seeing was mid 700's.

and with the proper turbo setup on a V8, there is no turbo lag, or atleast none that can be felt

4 cylinders experiance lag because the motors cant produce torque on a level that can move the car while the turbos build up pressure. torque gets the motor spinniing faster to get the turbos spooled quicker. V8's on the other hand have natural power to get the car going and relatively small turbos will really get a V8 moving without any lag

That is why in drag racing you often hear of turbo cars “loading up” on the bottom end to compensate for this. Which does improve low end performance

with a auto car and high stall, that will automatically bring the Boost up. the stalling effect will build boost.. like brake boosting the manual cars or stabbing the gas at a specified rpm

LS2 KLR · Apr 30, 2005

Red35th said:
Joe what's up with your current motor? I would think that with some new pistons to lower the compression that you could reuse the rest of your shortblock.

And you just finished up your current set-up too, lol.

Best of luck with all of it...

I'm hearing a little knocking, lol. I had heads installed recently and haven't checked the oil in two weeks. It was alittle low and I think I screwed up a bearing. I always planned on stroking with a sc if something ever happened. I'd rather just bite the bullit and spend the money now. I have $7k to spend so I'll have to wait on buying the charger for alittle while. I plan on fixing whatever is wrong with my shortblock and selling it with the cams. I'm just trying to figure out who I need to order a block from monday

Notched · Apr 30, 2005

best bet would be to get a VT engine.. very very strong and reliable, and ive only heard good things about there shortblocks, and more about the long blocks

stangman · Apr 30, 2005

LS2 KLR said:
I'm hearing a little knocking, lol. I had heads installed recently and haven't checked the oil in two weeks. It was alittle low and I think I screwed up a bearing. I always planned on stroking with a sc if something ever happened. I'd rather just bite the bullit and spend the money now. I have $7k to spend so I'll have to wait on buying the charger for alittle while. I plan on fixing whatever is wrong with my shortblock and selling it with the cams. I'm just trying to figure out who I need to order a block from monday

www.modularpowerhouse.com

they have a deal going on with their 302 stroker motors right now

LS2 KLR · Apr 30, 2005

stangman said:
www.modularpowerhouse.com

they have a deal going on with their 302 stroker motors right now

Theirs is about the same as the VTs. I'll give them a call on monday and see what they have to say, thanks.

white99gt · Apr 30, 2005

Orr89rocz said:
unless its a turbo...

blowers are run off the crank pulley so are constantly stuffing air into the motor, at all rpms.

turbos however build boost with exhaust gasses as rpms go up, so at lower rpms, its not boosting much at all compared to the blower. and i have yet to see 800-1000rwhp+ blown streetable cars that are as streetable as a turbo setup with same power. just my view of things and what i have see throughout the years

Guess you havent looked around much.

When just cruising there is ZERO boost.Streetable.Mine can get 19+mpg on the highway with the a/c on and sit in daily traffic for hours with no issues.

A far as the KB setup..NO turbo can even come close to spooling as fast as a twin screw can.

Turbo setups are nice.But also require new k members and other tweaks special to them.They put off a LOT of heat compaired to a supercharger.And most turbo kits have a really picky curve.A kb has a nice torque curve from 2k to 7k which makes cars more fun to drive.

The KB test car vs a new viper
Right click and save as:
http://www.kennebell.net/FORUM_PICS/brent10335.wmv

I dont see a turbo coming close to spooling that quick.

Gearbanger 101 · Apr 30, 2005

Orr89rocz said:
thanks for the info, but still, i believe its more streetable for turbo as i havent seen any super high horsepower cars running blowers, that are streetable

most KB hp i was seeing was mid 700's.

and with the proper turbo setup on a V8, there is no turbo lag, or atleast none that can be felt

4 cylinders experiance lag because the motors cant produce torque on a level that can move the car while the turbos build up pressure. torque gets the motor spinniing faster to get the turbos spooled quicker. V8's on the other hand have natural power to get the car going and relatively small turbos will really get a V8 moving without any lag

I know different, but I guess we'll just have to agree to disagree. Lets just say, that if you want big horsepower, you're going to need a big turbo, which isn't going to spool as quickly in comparison to a small one. If you want to improve the bottom end by sizing your set up with a smaller turbo, then it's going to affect your ability to make power up high. It’s a double edged sword. You’ll just have to be satisfied with making less peek horsepower with a small turbo application to improve your bottom end, or try to compensate with gearing and stall speeds with a big turbo to minimize the effect of boost lag.

Orr89rocz said:
with a auto car and high stall, that will automatically bring the Boost up. the stalling effect will build boost.. like brake boosting the manual cars or stabbing the gas at a specified rpm

This it true, but what good is this in traffic or a low speeds. It can be done, but it's a real PITA to continuously break boosting at low speeds just to avoid the turbo lag. Not a problem with a positive displacement blower. does matter if you're at a stop, roll or part throttle. Just throw and go.

I'll agree with you anytime you want with regards to turbo's having the ability to make far bigger peak horsepower and torque with less effort, but not with their comparison in drivability or right off-idle torque and horsepower. The roots and screw blowers still can’t be beat.

What do I need for 600+rwhp?

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