[BLOWN2V]

Originally Posted by dcook_14 So... 450 hp at 12# of boost is not safer than 425 hp at 14# of boost? Where's the best place for the IAT? haha, I guess a better question would be What is the IAT? I think it's the thing that comes off of the plenum and connects to your intake tube but I'm not sure. If this is true, it means I just bought a couple of pulleys I'll probably never be able to use until I go forged... if that ever happens

thats correct 450 at 12lbs is NOT safer then 425 with 14lbs... what you need to watch is with more boost it can heat the air more but either way a street driven car will be better off with a intercooler or at least some type of cooler wether it be a intercooler,aftercooler or meth

[Scott2001GT]

so a 450rwhp 2v will safe with a good tune and cool intake temps even at 14psi?

[BLOWN2V]

Originally Posted by Scott2001GT so a 450rwhp 2v will safe with a good tune and cool intake temps even at 14psi?

you can cant say anything is safe with the stock bottom end of these cars...

I have seen guys with a good tune blow it up with 375... i have seen guys push to 550... it really is a crap shoot on how long it will last... but a good tune will go a long way in how long it does last...

the point I have been making is the number that shows on the boost gauge take it with a grain of salt cause a lot of factors go into what kind of reading the gauge gets..... when seting a blower car dont worry about boost only the power lvl.... to many people are stuck oh my car only made such n such boost... but the numbers are good but I want more boost blah blah..... I dont care if mine is making 2psi as long as it makes power.... boost is just that a number....

the boost nothing more then number... if I were D/D my car i would keep it at 400 or low 400s....

mine is not normal lol... I make over 450 with a unlocked converter thru a C4 which would show over 500 with a 5speed... is it safe no am I lucky yes..I have no cooler at all running 19 degrees of timing and spin it 6700 everytime I go down the track

but I also dont D/D it and only run it on 110 oct leaded race gas

my car is a stock shortblock ...stock heads...stock valve springs... as in the motor has never been out of the car and the heads have never been off the motor...... like i said its not normal... I went as far as to boroscope the bottom end just to make sure I didnt have a built motor in he car since I bought it used with 20k on it and nope its the stock motor so i reaaly dont get it

[Scott2001GT]

so low 400rwhp is OK for these cars with a good tune and intercooler?

[Eagle2000GT]

Scott, I've just noticed that you have an automatic. The numbers that people throw around are those typical of a car with a manual shift transmission. Your car will have a greater parasitic loss through the drive train. The rule of thumb is that a manual transmission looses 15% and an automatic looses 20%. Dyno test seem to indicate that the loss through a manual transmiss is closer to around 12%. Either way there is a significant different in parasitic loss between a manual transmission and an automatic transmission.

It not the power at the wheels that blows motors. Its the power at the motor. All of the tuners I've talked to say to keep a daily driver around 380 rwhp (manual transmission). That is a conservative number that should hold up on the majority of motors. Some say 400 rwhp (manual transmission)is OK. Using a 12% parasitic loss thats 454 hp (400/.88) at the crank. That is right at the 450 bhp that most believe our rods can safely hold. But if you push a car with an automatic transmission to 400 rwhp you end up with 500 hp (400/.80) at the crank. That is past what is normally considered safe. I would recommend that you not take an automatic past 350-360 rwhp.

[Eagle2000GT]

Originally Posted by BLOWN2V this is not true.... boost doesnt kill motors....boost is nothing more then a measurement of back pressure in the intake track and thats it it has nothing to do with flow or amount of air.... for example.... you take said car that is making 450 with 14lbs of boost... add ported heads,cams longtubes and intake manifold now said boost read 8 but power is 550.... is that 550 safer then say a car making 550 with 15lbs nope... its not the whopping 15psi worth of pressure that kills the motor, cause it takes the same force on the piston to make 450 n/a as it does to make 450 with 1psi or 1000psi of boost its still the same force on the piston n rod another example in your way of thinking with cams n longtubes and such will lower the boost how does it lower the boost... it lowers the boost number by getting rid of restriction but it still the same amout of air if not more air getting into the chamber... thats why the boost number goes down and power goes up.. in no way will it bleed off pressure to make it safer...well unless you are running to big of N/A cams with a blower but then its not safer cause now you risk burning up the exhaust valves ... I know its something someone told you on the internet but it is just interweb BS

I disagree with you a little. It is stress on the rods that breaks them, not rwhp. There are lots of stresses inside the engine and if you remove some of the effort it takes to push exhaust gasses out of the cylinder then you have taken some of the stress off the rods. It is known that boost drops and horsepower goes up when you put on long-tube headers and an o/r mid-pipe. But the stress on the rods has remained about the same. Therefore, this combination of mods is safer at a particular horsepower level, let's say 400 rwhp, than just throwing more boost at the motor.

[dcook_14]

Fuck I'm confused...
I'll see if I can just go to a dyno this weekend and see where I'm at. Depending on how much I'm below 400 I'll pulley down from there. I know boost is just a number, but when you don't really have any other mods, boost has alot to do with rwhp

[Scott2001GT]

yeah thats understandable. I am not in the market for a blower but tryin to get info b.c I would like to someday in the next few years. Prob do internals not long after the blower when I do.

[dcook_14]

Found these posts on another site


From Wiplash: D1SC, 3.4" pulley, stock longblock it made 457/462 while flowing WAY too much methanol. I made a pull without the methanol and 11 deg's of advance and had to shut it down at 5200 because it was getting close to 13:1 but it was already making 427rwhp so who knows what it could have made at 6200...this was on pump gas.

At 3000 it was 350rwtq and at 3500 it was already at 400rwtq!


From Erich:
Mark VIII motor
cobra crank
manley rods
diamond 9cc dish pistons
03 cobra cams
98 cobra intake
03 cobra exhaust manifolds
Procharger D1SC 3.4 inch pulley
SLP catted X pipe
Tuning by Dave at SGS

Initial tune with nasty plastic procharger blower inlet pipe and small air filter plus stock ford catback. 489 hp/439 tq 17-18 psi boost Air filter was flattened. 23 degrees of timing

Changed to homemade 4 inch powerpipe and Pypes race pro catback. This time first pull was cut off at ~6000 rpm making 537 hp and climbing. Boost heading towards 20 psi. Dangerous situation with 93 octane. Cut the timing back to 20 degrees and got spark blow out. Gapped the plugs down from 0.032 to 0.024.

Final numbers 527 hp/463 tq with a nice safe tune for pump gas. 20 psi boost at 7000 rpm. Gains over the previous tune increase thru the entire powerband. Unfortunately raining the whole day and weekend, did not get to have much fun with it.

So as it turns out, it was good to get it tuned again. I had thought I heard some detonation after the powerpipe when running hard in 3rd and 4th (always let off at the first sign).




These are obviously different applications that what I have, but it gives me a ballpark. The first one would be more of a number like I would see since he was also on a stock 2v longblock. The second one is putting out big numbers, but his compression with those pistons is close to 9.5:1

Here are the links to the actual threads

First Setup ~460 rwhp

Second Setup ~540 rwhp

[Scott2001GT]

Originally Posted by Eagle2000GT Scott, I've just noticed that you have an automatic. The numbers that people throw around are those typical of a car with a manual shift transmission. Your car will have a greater parasitic loss through the drive train. The rule of thumb is that a manual transmission looses 15% and an automatic looses 20%. Dyno test seem to indicate that the loss through a manual transmiss is closer to around 12%. Either way there is a significant different in parasitic loss between a manual transmission and an automatic transmission. It not the power at the wheels that blows motors. Its the power at the motor. All of the tuners I've talked to say to keep a daily driver around 380 rwhp (manual transmission). That is a conservative number that should hold up on the majority of motors. Some say 400 rwhp (manual transmission)is OK. Using a 12% parasitic loss thats 454 hp (400/.88) at the crank. That is right at the 450 bhp that most believe our rods can safely hold. But if you push a car with an automatic transmission to 400 rwhp you end up with 500 hp (400/.80) at the crank. That is past what is normally considered safe. I would recommend that you not take an automatic past 350-360 rwhp.

I would say if I was to ever boost I would do around 380rwhp.

[Eagle2000GT]

If you go to 380 rwhp with an automatic transmission (475 bhp) you need to get mods that help your stock rods and pistons hold up to the strain. Cams and headers are important. The 380 that tuners suggest is through a manual transmission.

[dcook_14]

We're still kinda debating on whether or not cams and headers would actually help or hurt the situation.

The question is, is it the amount of boost that is hard on the internals or the amount of horsepower? I know it's kinda a combination of both, and usually boost amount has a lot to do with horsepower. But if I got LTs, it would lower boost and increase horsepower. We're wondering whether that would be good or bad for a motor close to the breaking point.

[BLOWN2V]

Originally Posted by Eagle2000GT I disagree with you a little. It is stress on the rods that breaks them, not rwhp. There are lots of stresses inside the engine and if you remove some of the effort it takes to push exhaust gasses out of the cylinder then you have taken some of the stress off the rods. It is known that boost drops and horsepower goes up when you put on long-tube headers and an o/r mid-pipe. But the stress on the rods has remained about the same. Therefore, this combination of mods is safer at a particular horsepower level, let's say 400 rwhp, than just throwing more boost at the motor.

the stress on the rods n piston DO NOT STAY THE SAME... it takes a certain amount of force on the crank to make a cerain HP...yes its not rear wheel horsepower cause if you use a turbo the motor is maing lees CHP to reach the same RWHP that a blower would because your not wasting power to spin it..

headers work by getting the gasses out so the chamber can be filled completely with fresh air n fuel where a restrictive exhaust is not going to get it all of the exhaust out so you will have some exhaust in the chamber when it fires... and they do this for the sake of emisions.... they do not put less pressure on the rod and psitons... same goes for cams...

boost is read on the pressure of the intake manifold so when you add cams they let more air into the motor so the manifold pressure goes down that is because a crap load more air is getting into the motor which in turn ADDs more stress to the rods n piston which is why you get more power....

boost is just that how much pressue is in the intake manifold and thats it.... you add bolt ons that increases the power well that increases the stress on the rods n piston

[BLOWN2V]

Eagle.. not to sound like a dick.. but where n hell are you getting this BS info from.... I looked at your page and I dont see what you have done to your car to base your ex off of...

I dont know eveything just like so many of us I learn new stuff everyday.. but the info I do have is from building cars and helping and learning from a few racers that race in the low 7 high 6 range... as well as talking to my tuner which also runs his own mid 7sec mustang on a 10in tire

if you look at the motor as what it is a (big air pump) maybe it will make more sense...
more air in= more air needed out= more air out mean that can be pumped in...=== MORE POWER and more stress
but at no point does the internal stress of a supercharged motor go down...

[dcook_14]

Makes perfect sense to me Blown2V. I'm going stick with the pulley I have and just do supporting mods to try an get the power where I want it.

That is until I get a forged motor put in there Then I'll pulley down

[Scott2001GT]

Originally Posted by Eagle2000GT If you go to 380 rwhp with an automatic transmission (475 bhp) you need to get mods that help your stock rods and pistons hold up to the strain. Cams and headers are important. The 380 that tuners suggest is through a manual transmission.

well baker is making 427 on stock internals with a manual. So if I got a supercharger I would prob do plenum t/b and LTs. Then build the engine.

but 380rwhp should be ok i think with a solid tune.

[Scott2001GT]

haha me talking about a supercharger lol ahh the dreams we have!