djay86

Before anyone knocks on this topic.. I have searched various keywords coming up with nothing..

Originally I wanted to build an all motor ls with a b20 bottom. Now I'm not sure if it will be worth it, but I already have most of the parts including stage 3 crower cams.

If I wanted to boost 8 PSI, and also run these cams, wouldnt it make a good bit of power? I always hear "overlap" and I'm not exactly sure what it means.

Type R's are turboed frequently without much problem. How exactly is overlap dialed out? and is it possible with stage 3 cams..

Hope I get some good responses.. thanks.

t04ecvc

Its not that you can't, but usually you get better #'s with stock gsr cams or somthing with simular lift and overlap. I run the Crower turbo cam personally and they make power up to about 9200 rpm.


Modified by t04ecvc at 7:32 PM 1/4/2004

.dave

Overlap occurs when the intake and exhaust valves are open at the same time. The periods of open duration for the intake cam and the exhaust cam "overlap." Having cams like this on a turbo engine hurts performance, because some of the air is blown through the intake ports and out the exhaust ports. Overlap can be dialed out with cam gears sometimes, but I am not sure about the cams in question. It depends on how much of an overlap they had.

JalopySiR

I wouldn't worry too much about it. I had EF-1 cams in my turbo B20. Nothing but gravy. Car absolutely slammed into the rev limiter. Just get cam gears. Big is fine for turbo.

Altered

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JalopySiR &raquo;</TD></TR><TR><TD CLASS="quote">I wouldn't worry too much about it. I had EF-1 cams in my turbo B20. Nothing but gravy. Car absolutely slammed into the rev limiter. Just get cam gears. Big is fine for turbo.</TD></TR></TABLE>

Turbo motors like a little lift but not much duration

JalopySiR

I really wouldn't sweat it. This is firsthand, not heresay thru friends of friends. Tell me why they don't like duration. I think you may be confusing duration with overlap. You should talk to Robert Martin at EF-1.com. I've done it. It worked GREAT.

boosted92

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Altered &raquo;</TD></TR><TR><TD CLASS="quote">

Turbo motors like a little lift but not much duration</TD></TR></TABLE>

Turbo cams love lift, and as long as you don't mind sacrificing spool, love duration as well. With a typical VTEC x-over of 5500+ I think your turbo would be fully spooled and I think the car would make a lot of power. I say try out the stage 3 cams, and if the dyno results suck then i'll admit that I was totally wrong

Altered

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JalopySiR &raquo;</TD></TR><TR><TD CLASS="quote">I really wouldn't sweat it. This is firsthand, not heresay thru friends of friends. Tell me why they don't like duration. I think you may be confusing duration with overlap. You should talk to Robert Martin at EF-1.com. I've done it. It worked GREAT.</TD></TR></TABLE>

Ive talked to Javier from JG, Paulus from AEBS and Brad from RLZ about this topic at one point or another over the last few years. Ive never seen any high HP turbo motors come from Rocket or much anything from him really at all so Im still pretty sceptical about the performance of his products. Hopefully as time goes on there will be more people using his stuff, providing everyone out there with more input and possibly dyno sheets on his products. Im a fan of the little guys out there so I hope he does well, his prices are great cant argue that

JalopySiR

I had his cams. They were awesome. L21s, B20, HKS Manifold, Nissan Pulsar GTi-R T28 (.60a/r T3 compressor w/ 60trim wheel, .86a/r T25 trubine housing w/ 79 trim wheel), Skunk2 IM, AFC/450s, cam gears. 210hp/190tq@6PSI!!! ... at 6000RPM.. redline isn't until 7200. 175tq from 3500+ Search for topics I created for the plot. This was in a CRX. Nastiness.

danimal

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by djay86 &raquo;</TD></TR><TR><TD CLASS="quote">Before anyone knocks on this topic.. I have searched various keywords coming up with nothing..
</TD></TR></TABLE>

you came up with nothing because most of us really don't understand the effects of overlap and cam timing on boosted engines... claiming that something "works" because it feels good with the butt dyno is a time-honored tradition.

these days i want to see the math before i lay down my $$$... so i've tried to read everything i could about turbos... one thing that keeps cropping up is what the pressure differential is on both sides of the turbo... there is a great read on the subject at http://www.grapeaperacing.com/...s.cfm.

what you need to do to check how well you matched the turbo and cam to the engine is to monitor that pressure differential... try finding anybody out here with those numbers! it requires boost gauges on both sides of the turbo.

porsche actually did come close to getting that 1:1 ratio with the early 911 turbo engines, which was amazing considering that they made all their power way down low... high-revving honda motors make it much easier, but i would still not run an all-motor hi-po cam if i was you... the cam timing is too critical to "dial out" duration that is simply too much to begin with.

there is also a lot of data out there that suggests that increasing the exhaust flow(e/i ratio) is a really good thing for a turbo motor... and of course the camshaft has to be designed around that... i've seen non-honda turbo engines that had exhaust flow that was nearly as good as the intake flow, and they made big power... some people even run exhaust valves that are the same size as the intake valves.

also check out "forced induction performance tuning" by a. graham bell, copyright 2002, it's far superior to anything corky carroll ever wrote... there is some great boost theory in it.

nevin

.

Chillinit

i've heard of crazy idling issues with stage 3 cams...I wonder what will happen when they are used with a turbo application!

mike1114

iTrader: (1)

I'm in a similar situation right now, I'm not saying the stage 3's will or will not work but I have crower stage one vtec cams in my turbo gsr and I am switching back to stock to see if thats better!

Once my vtec hits, there is a huge dip on the dyno chart of like 25whp and then my tourqe just levels off and stays there till redline.

I have seem many similar setups to mine usually yeild about 20 whp more than me total and quite a bit more tourqe that did not level off, just kept rising.

djay86

anybody else for the hell of it?

hpfsi

All you can do is try. I have a set of Toda C cams that I plan to test out. With the right setup big cams can work. I have a Honda engine building book with a 769hp dyno from a JG built b18c5 - 11:1 cr, a T4 turbo and 296/300 cams (duration @ zero lift I'm guessing). Take what you want from that.... unfortunately I won't have any hard evidence either way until I test the cams myself. I like the fact that oem Honda cams aren't a limiting factor (with plenty of monster engines running R or Gsr cams), but there is always room for improvement. If cost isn't an issue then why not experiment. If the C's don't work for me I'll trade them for some spec A's. If those aren't what I'm looking then ITR cams it is!


Modified by hpfsi at 7:20 AM 1/6/2004

haggar

The issue is mainly overlap.

As was already mentioned, if there is a large amount of overlap, you will actually bleed off pressure inside the cylinder as the intake charge gets sucked out the exhaust ports.

In a naturally aspriated engine, overlap is beneficial for high rpm motors. You leave the exhaust valve open a little while after the intake valve opens up. The exhuast moving helps suck the intake charge in, because in a NA situation, the engine has to SUCK the intake charge into the engine. the exhaust velocity does have scavenge the cylinder. The higher the RPM, the longer you have to leave the valves open to get things to work correctly.

In a FI setup, the intake is pressurized, so the whole timing of everything is different. Air moves into the engine much faster, so the intake duration doesn't need to be as long, nor is as much overlap required. But you want more lift, to open the valve wide to allow the pressurized charge to enter quickly.

DLB1994

i have a set of big cams but i have a nonvtec ill see the whp gain off mine soon

ladysman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Altered &raquo;</TD></TR><TR><TD CLASS="quote">

Ive talked to Javier from JG, Paulus from AEBS and Brad from RLZ about this topic at one point or another over the last few years. Ive never seen any high HP turbo motors come from Rocket or much anything from him really at all so Im still pretty sceptical about the performance of his products. Hopefully as time goes on there will be more people using his stuff, providing everyone out there with more input and possibly dyno sheets on his products. Im a fan of the little guys out there so I hope he does well, his prices are great cant argue that </TD></TR></TABLE>

Javier at JG is a complete CROOK.

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ladysman &raquo;</TD></TR><TR><TD CLASS="quote">

Javier at JG is a complete CROOK.</TD></TR></TABLE>

Javier is a great man. To me he is the God Father of imports.

Rocket

We've done testing, and I pretty much know the limits of duration that will work for turbo.

Anything 2 steps larger than say CTR is going to be on the edge of being to big.

1SlowSi

When i go turbo do you think that stock Si cams would be fine? Because i dont have my CTR cams anymore, and i can get Si cams for free. Would you go any higher that Si's or maybe buy the CTR's again. thanks!

Finest

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by haggar &raquo;</TD></TR><TR><TD CLASS="quote">The issue is mainly overlap.

, you will actually bleed off pressure inside the cylinder as the intake charge gets sucked out the exhaust ports.
</TD></TR></TABLE>

Actually, it would be PUSHED out the exhaust side.

An ideal "turbo" cam would have more lift, not duration. Just make sure the rest of your valvetrain can handle the additional lift and rpms.

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1SlowSi &raquo;</TD></TR><TR><TD CLASS="quote">When i go turbo do you think that stock Si cams would be fine? Because i dont have my CTR cams anymore, and i can get Si cams for free. Would you go any higher that Si's or maybe buy the CTR's again. thanks!</TD></TR></TABLE>


ITR is good for turbo on 1.8 BVTEC motors.