also, trading compression in the B16 for the displacement in the B18/B20 decreases spool time and there is also more volume for the intake charge to fill and has more time to fill it with the slower moving piston, this, of course, makes more power.

 

Horsepower is a function of torque and RPM. Speaking VERY generally, if the B18B does make more torque, the B18C1 would only make more horsepower because it's revving higher.

 

Without saying any of you are wrong, static numbers are just that, static. You can boast about numbers all day long, work the math, and do your thing. When you want to try a real comparision, put two identical cars on the track configured based upon your numbers and see who runs the 1/8 mile faster and the 1/4 mile on a street tune. In the case of lower compression, fine you make 400whp ON THE DYNO, now a days it seems like a standard to make that much, big deal. Your buddy only makes 325whp because he has the dreaded 10.2:1 compression. You guys go out for a night on the town with your ladies and you roll up to a light after the movie, around 1am, no one is around. You both turn to eachother and are thinking the same thing. Light turns green, tires light up, gone, but why did your buddy just slam 2 car lengths on you FROM THE LINE? Oh yeah, thats right, he's got torque, he can spool, he moves. So you keep runnin up the speed, hit 100mph and letoff to avoid speeding into the closly approaching main st. area (lots o pigs). You lost - Oh wait, but your buddy only made 325whp? wtf?

We are talking about Street HP here, nothing more. If you can make 400whp thats all fine and dandy but if it takes 3 years to make it, how is it usefull? A fun test would be to plot HP vs Time for the two motors used in the example above. The one thing everyone must keep in mind is that the turbos WILL be sized differently due to the different boost requirements fitted to the engine.

Also, just a comment, with all this talk about how many pounds per hp, I think some of us forget that the boost pressure is a measure of how much resistance the engine creates to the air being forced into it. Take for example a cocktail straw, one of those little tiny red jobbers. Blow into it as HARD as you can and feel the air comming out, also notice how fuggin' tired your *** is. NOW take one of those HUGE straws that come with the giant pixisticks and cut it to the same length as the red straw, then proceded to blow into it as HARD as you can. You run out of breath much faster eh? but your diaphram isnt killing you and you noticed much more air come out of that straw in a shorter amount of time. Use this and compare it to Horsepower vs Boost pressure. Boost numbers on a 2L b20VTEC with a b16a intake mani and stock valve seats are going to be much greater than the same motor with say a VICTOR X manifold and 1.5mm oversize valve seats matched with a ported IM.

Relating this to IB's motor, yes they only have 13psi but I bet if you measured CFM it would be through the roof on that engine. They probably did an extensive job ensuring the intake tract is unrestricted and they have the proper cam timing. I'm sure there's efficency to play in but for thte moment its left out.

Anyhow, just thought I would point that out! '

Peace


[Modified by stizzit, 1:02 PM 9/28/2002]

 

i think one thing you are forgetting is that a higher compression motor running less boost will be burning less fuel and less air which equals less HP, a lower compression motor will burn more fuel and more air and have more HP.

Am i right??

 

for a street motor i would have to say go 9-1 but if its a race car go 10-1+

 

This is actually a post toward 2 people above.

And all I have to say is this.

With weight being equal...

The HIGHER average HP car is always going to have an advantage. Always.

Revving higher is always better, bottom line. The higher the motor revs, with a flat to steady HP curve, the HIGHER average horsepower your going to have...

And ALSO the lower the torque, so you have less wheel spin.

The 400 WHp car would absolutely destroy the 325 WHP car...

All you need is 1 thing. Scramble boost controller.

You could never launch a 400 WHp front wheel drive car in first gear on the street. No way.

Scramble boost, means game over...youll hook up better, and 3rd gear will be a massacre.

Back to lower revving motors...

They are NOT good at all for a honda for the following reasons...

#1 They can't breath. The power curve will go up fast, and DROP off fast...giving you an incredibly bad average HP rating. A motor that revs higher will have to breath better, and breathing better means you have a flater HP curve, which always translates into a higher average HP number.
#2 The higher revving motor will have less torque in the powerband. This means it is less likely to break the tires loose. If the motor is making its maximum torque in the middle of your powerband...your way more likely to break those tires loose.
#3 the higher your motor revs, the more MPH you can go in each gear. A TOTAL advantage! Which gear pulls the hardest? FIRST GEAR, then 2nd, etc etc etc...because the parts don't have to work as hard...If I can go 50 MPH in first gear, and your low revving motor has to shift at 25...your going to get taken out of the hole rediculous style. I use Ericks Racing's car as an example...rediculous fast out of the hole...


I could write a book on why to build a motor a certain way, and why lower compression turbo motors are just superior in every way, and why higher revving turbo motors are absolutely the best... And I might.

I have 1 book to write first...and most of you know what that is about.

lol.

Thanks for sharing you guys. Thank you all for not turning this into a:

"you are dumb, and I know better" post. I think everyone's opinion counts and people will decide for themselves.

One more example of why lower compression is better for boosted cars...

ALL of the manufacturers use big DISH pistons for their turbo cars..

Toyota, Nissan, Porsche, etc..

because they know that dish pistons and a combustion chamber shaped like an "egg" of you will...is way more effecient and makes supreme HP.

Thats why they didn't make higher compression with lower boost...

I didn't invent alot of my theories on motors...myself. I looked at what the best engine builders in the world did, and started with that basis.

I studied motors for years. And I have my theories of what is supreme and what is not.

Thank you all again./

Jeff

 

I think the issue with there being more stress on the higher compression motor is concerned with the amount of compression when NOT boosting. If you're just cruising, then the compression is 10.4:1 vs. 9.0:1....

That is a good point about there being more air in the combustion chamber of the lower compression, higher boost motor, but I'm not quite sure if that is true (though there is certainly more volume) or if it really matters, since volume makes no power without compression and the other motor certainly has more compression...

so, I guess my d16z6 is better than all yall's b-series, since it has a 9.2:1 CR

EDIT:
Importreview: Did that pitbull really run the 1/4 mile on the bike? I hope he had a doggie helmet .


[Modified by ion_four, 11:53 PM 9/28/2002]

 

you some kind of animal rights activist?

That pit bulls head is harder than a baseball bat.
lol/.

Jeff

 

he's right, I have a pitbull...and her head is like a steel football...if you can picture that...hehehhe

 

The B18a/b has 9.2:1

 

high compression and little boost is the same as low compression with lots of boost. but the one with more boost has more tq there fore a better powerband while the one with little boost high compression has a bitter respone.

oh and last your d16z6 is not better. the head flow of b engine out weight you.

 

you do realize this is over 3yrs old right?

 

I am building an 11/1 turbo motor. I'll post the graphs when it is done. Just waiting for my S300

My 2 cents,
High CR is better for intened HP bellow 400 and is more fun on the street

Low CR is better for high HP apps, better on the 1320

 

Well this is old and interesting. But cuz it was brought up I have a graph for a low compression S2000 making 360hp. With this I am giong to compare my graph with this graph and look at the power under the curve. Then I can post closer to apples to apples between the two set-ups. It will be interesting.


-Chris

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by swapdohc &raquo;</TD></TR><TR><TD CLASS="quote">High CR is better for intened HP bellow 400 and is more fun on the street

Low CR is better for high HP apps, better on the 1320</TD></TR></TABLE>

You say this because you havn't had a high compression street motor before

I had my 84mm GSR motor built at 10.5:1 compression and it was nothing bit a disapointment. All this made up quicker spool and better off boost response was nothing, and I even read this thread thinking holy **** I'm going to make so much power. I rebuilt the motor with 9.3:1 CR pistons and it is a lot more fun on the street. The only way I would ever do a high comp turbo motor again is if they happen to start pumping C16 for 2 bucks a gallon at shell

 

i agree with import review.

**** math, and static this and that.

experience and seeing actual cars woth the different setups and how they compare owns all. i have a friend with 9.1:1 with 447whp on 20 psi, it doesnt feel any different starting off then a regular b16a or gsr.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GiNuWiNe &raquo;</TD></TR><TR><TD CLASS="quote">you do realize this is over 3yrs old right?</TD></TR></TABLE>

Lol.

 

This is great! I have to save this one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kamAccord &raquo;</TD></TR><TR><TD CLASS="quote">This is great! I have to save this one.</TD></TR></TABLE>

Except ignore it because it isn't true My 9.3:1 motor at 15 psi feels just as strong if not stronger than my 10.5:1 motor on 14 psi, only difference is on the 9.3:1 motor I still have the ability to run more boost on pump gas.

 

well high compression with boost is better and fast better everything if you pumping racing fuel. but we are not. we are stuck with 92 to 93 depending onpone where you go. so for that low compression is the key. and no i didn't read the date haha...