tell me what rpm you want to be

tuned for and I'll give you an estimate for runner length

 

right now, he shifts at 6800 w/ the stock gear ratios. im not sure what RPMs the upshifts land him at.

i think he wants to rebuild his motor too, so lets say he is going to move his shift points up 1000 rpm, just incase.

can you get me numbers supporting a 6800 shift point and a 7800 shift point?

 

whoops

OK it was late... I need to know the opening and closing events of the cams as well.

by the way, what is this car going to be used for?

If he plans on using it in the street I wouldn't tune the intake for max power. A better philosophy is to tune the intake for lower rpm (increase off boost performance and improve driveability) tuning for offboost will also improve spool time.

But it's his car and I'll give an ESTIMATE for whatever he wants..

 

i cant find any production cams that list their intake and exhaust valve events,just duration and lift.
crower has; 242/245 advertised, 196/198 @ .050", and .411" and .391" lift w/ 1.7 ratio rockers. sorry i couldnt find better info.

but this is going to be a strip only car. so we want max power, and to move the torque peak higher. hes got tons of torque in the mid rpms as it sits now.

the car will NEVER bee off boost. he has a stutter box, so he has 6psi even while sitting still. we wont need to worry about off-boost torque or low end ddriveability.

thanks
chris

 

Unfortunately,

I need that cam info before I can give you an estimate.. keep looking if your still interested....

 

Re: Unfortunately,

I need that cam info before I can give you an estimate.. keep looking if your still interested....

How long would the runners need to be, if tuned for 6500 rpm with stock cams?

Rogue

 

What do you mean by event?
Also I might as well butt in here. Here are some cam specs is this enough:
Intake Duration 250@006 Lift .374 inch
Exhaust Duration 250@006 Lift .374 inch

If so than with my 420A engine and for a tuned high rpm of 7500 what size runners should I have?
thanks

 

guys he needs to know the Valve events. not just the duration and lift.

he needs to know the Intake Valve opening, Intake Valve closing, Exhaust valve opening, and Exhaust valve closing.

these valve events are measured in relation, to piston position.

say for instance, the intake valve opens 8* Before Top Dead Center, stays open and closes 4* AFTER Bottom dead center. then it compresses, fires and goes back down on the power stroke. now the Exhaust valve may open 4* Before Bottom Dead Center, stays open as the piston goes up the bore, and closes 8* AFTER top dead center. and the is also a certain amount of time when the piston is At top dead center, and BOTH the intake and exhaust valves are open to help in evacuate the cylinder of the exhaust gasses. this is called Over lap. the longer the overlap, the better the power will be in the upper RPM's, but will have poor idle quality and low end power. to have GOOD idle and low end power you have a SHORT overlap, if you have any at all. now, having little or no overlap means that you will not create as much upper RPM horsepower as you would w/ a cam w/ long overlap. you measure the over lap w/ the Lober Centerline angle. cams w/ LONG over lap will have as small as 106* centerline angle, meaning its narrow and the 2 vavles are open at the same time. the wider the angle, say 118* centerline, the valves are open a Shorter time.... but these are all imaginary cam specs. and arent from a real cam.

does that 'splain anything?

chris

 

FOUND THEM!!!!

anoldsman

Specs on HKS 272 I/E Cams
I have the spec cards for the 264 and 272 cams in english. They are as follows:
264 Intake
Max Valve Lift - 10.3mm (0.4055")
Centerline at 0mm vavle lift 105 deg
Intake Valve timing at 1mm (0.0394")
Valve opens at 2 deg BTDC
Valve closes at 28 deg ABDC
Valve Centerline 105 deg (WRONG - 103 deg)
264 Exhaust
Max Valve Lift - 9.8mm (0.3858")
Centerline at 0mm vavle lift 117 deg
Exhaust Valve timing at 1mm (0.0394")
Valve opens at 42 deg BBDC
Valve closes at -12 deg ATDC
Valve Centerline 117 deg (CORRECT)

272 Intake
Max Valve Lift - 10.3mm (0.4055")
Centerline at 0mm vavle lift 105 deg
Intake Valve timing at 1mm (0.0394")
Valve opens at 6 deg BTDC
Valve closes at 32 deg ABDC
Valve Centerline 105 deg (WRONG - 103 deg)
272 Exhaust
Max Valve Lift - 9.8mm (0.3858")
Centerline at 0mm vavle lift 111 deg
Exhaust Valve timing at 1mm (0.0394")
Valve opens at 36 deg BBDC
Vavle closes at 2 deg ATDC
Vavle Centerline 111 deg (WRONG - 107 deg)

Notice that the 1mm timing is off from their spec card. Either the card is wrong on the open/close points or the centerlines are wrong.
Feel free to double check my math. I hope that this helps.

Chris
1992 AWD Tsi

Tondar, can you figure it out for HKS 272/272 combo? since this will be a strip-only car.

thanks
chris

 

ok

give me a couple of days...

 

"okely dokely"

btw, while your at it, do you think you could find the figures for a 264/272 combo (for my car, a street/stripper)?

i appreciate your help

thanks
chris

IOU: one 6-pack.

 

best estimate

It should be noted that intake tuning is somewhat of a black art and very hard to "nail down" I'm going to use a simple theory that for a drag car should be somewhat accurate.

First off, if this is truly a drag car than put as large of a plenum as you can fit. Throttle response will suck but for drag only that doesn't matter.

Make sure to bellmouth the runners at the intersection with the plenum. I'm going to assume that for drag racing you are using either an air to water intercooler, or some other type of highly efficient intercooling, thus giving an intake air temp of ~90 F.

As for the rpm selection, assuming a constant boost pressure the tuned rpm should have the highest Volumetric efficiency and hence highest torque. Since horsepower peaks are higher than torque peaks and given your requests, I chose to tune for 6000 rpm. I'm making the assumption that you won't shift until after the HP peak.

Using the 272/272 combo, I ended up with an estimate of 7.5" for the length of the runners.

The diameter of the runners depends on how much power you want to make. The idea is to make them as narrow as possible without choking flow. A good estimate is to keep the velocity of the air in the runners below 75 meters per second. If I were you I would just use the same cross sectional area as the intake port.

Hope this helps some, and I like Amber boch beer for my six pack...

 

thanks bro.

ill pay ya next time i see ya. >) heheheh. then you can show me where it is that i can get the novelty beer.

chris

 

ill pay ya next time i see ya. >) heheheh.

I live in Detroit... I can come see you aaaannnnnyyyttiiimmmeee...
heheheheheheh

 

DOH!

well you got me there. you should visit toledo anyhow, theres 2 speed shops in town; Defcon motorsports and Showdown motor sports. showdown is DSM oriented, and Defcon is everything-oriented. im a fan of showdown lately, seeing as how i dont really care for the owner of Defcon, he can be...not nice sometimes. so i just avoid him.

anywho, cya later

chris

 

check this out

Although the runners seem a bit short, you'll be hard pressed to come up with a nicer unit than this:

http://www.rossmachineracing.com/intake.html

 

thanks bud. ill check that stuff out.

how bout that venom drag manifold, heard anything about those?

chris

 

No

have any pics????

 

venom drag manifold

looks kinda like the one in the link you sent me, but the Venoms are about $100 cheaper.

the runners are very short on those billit intakes.

this is what he sent in an email:

The intakes are $695. The distance from inside the plenum to the head
is
4.4". The distance from the valve to the head mounting surface i don't
have right now. How much horsepower you trying to make, what RPM, what
boost?

Thanks
Tom

 

Short!!

At 4.4" you probably wouldn't ever see the tuning peak, it would be off past redline. The intakes (both) do look nice and are straight shots at the ports which will minimize flow losses. I didn't see the inside of the Venom one but the link I showed you the runners were nicely bell-mouthed.

I guess it just depends on whether or not you can make your own for not too much more than this...

 

yea, i figured that.

i dont think that billet manifold is long enough to reach a sensible tuning peak. probably around 8000. i think those are much shorter than the lengths that you suggested. theres no reason to wind the piss outa the motor if you dont have to, itll last longer.

and agree w/ you on the Venom intake..the runners are insanely short for any kind of street duty. i cant belive honda boys actually buy them and think they make an improvement...

i can probably make the manifold for less than $700. my biggest hurdle would be transitioning the round runners to the rectangular ports. other than that, it would be a walk in the park...relatively speaking.

im gonna need some practice, since im probably going to have to make a custom turbo header for my trans am...hopefully i can build that whole car for $5000...

thanks
chris

 

go here......

www.sdsefi.com

then click on tech page/faq at the bottom.....

 

thanks sport, already been there. ive emailed the guy before too. its not all that technical, but some good pics. its definitly inspiring. thats what makes me think i can do it all myself. and im pretty confident that i can... i guess we will just have to see.

im going to build a 87-89 Pontiac Trans Am GTA, 350 SBC and single T66 running a blow-thru set up. its gonna take some finnageling to hook up the turbo header and crossover pipe. hopefully i can get it done for $5000...

chris

 

What harmonic (2nd,3rd,or 4th) are picking up when you are doing these tuning calculations for the intakes? Also remember that the tuning calculations are based on organ pipe tuning of yesterdays. Speed of sound changes with pressure, which should change the calculation even more with boost pressure. To correctly make an intake nowadays you have to design it for the specific engine you are building. That is done with computer simulation and flow analysis. If you have to ask "how much" you can't afford it. Most turbo engine builders are building intakes with very short runners trying to get the large amount of air in the engine as quick as possible with a big plenum to help distribute air evenly between runners.

 

tom, do you own a speed shop or something? for some reason i feel like ive heard about you.

btw, you are thinking of resonant tuning. which is affected by pipe diameter, length, and density of the air. this is all something they teach in physics. and its all relavant when tuning a manifold for an NA car. take TPI for example, the gm fuel injection.

ever see those Venom drag manifolds? man those runners are so freakin short. that would bump the top end up way up towards the redline.

its pretty important to mix the tuned runners into a turbo application, cuz the off-boost driving would suck, such as any time in town...its just that im wasnt exactly sure which measurments to use when i build my manifold..

chris