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Cam shaft selection with N20 use in mind (CamKing , racer7088 etc...)

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Old 07-10-2006, 11:39 AM
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Originally Posted by racer7088
Friendly Freddie,

I would back way off of the compression and run a lot wider LSA right off the bat if you are going for more power with the nitrous. Tightening your LSA BUILDS compression and certainly does NOT bleed any away! Anyone telling you that you need to tighten LSA as you add compression is just plain wrong or doesn't understand camshafts very well. Tightening LSA is for classes where you can't make good compression and/or where you have tons of exhaust flow and low backpressure compared to your intake capability.

Tightening LSA opens the exhaust later which hurts power on NOS and it also closes the intake earlier which increases cylinder pressure down lower in the rpm band but may even reduce power overall depending on the engine. With the compression you have I can't imagine needing too tighten LSA or advance the cam much at all! Tightening LSA also increases overlap which is also NOT where you want to go on a nitrous engine unless you have huge exhaust and even then 110 is too tight. It is just increasing reversion.

I would have a cam probably much wider in LSA with a fairly large split to the exhaust side in duration. You need to size your exhaust lobe such that it can handle along with your headers and exhaust system the power you are aiming to make on NOS. The cam you have is not one that is going to make big power on NOS probably. Your intake lobe is big enough but certainly not huge and you shouldn't really make power as high as you are turning it anyway.

Also If you could leave on a little less NOS and phase in the extra NOS at even higher rpm your gaskets will live longer. Most people spray too much too soon and the cylinder heads simply lift and /or detonate. The LS1 just isn't the greatest on the head gasket situation that's for sure! Spraying 300 at 2500 rpm is 600 ft pounds more tq and spraying 300 at 5000 rpm is 300 foot pounds more tq and spraying 300 at 7500 rpm is only 200 foot pounds more tq.
Erik , I will keep all of this in mind. Thanks for all of the usefull info. I hope we all learn somthing from this little experience of mine.

BTW, I have a progressive controler on the car. I leave on 10% of total power and ramp it to 100% over about 1.5 seconds. The car 60 fts 1.21's and 22's pretty consistantly on a good track. I have never had spark plug issues and A/F ratio is very conservative. I think fuel and N20 is divided pretty evenly because of the Carb style intake. I say this, because I don't think the tune is the issue here. I would'nt want to back it down any because the 60 ft is what makes the car a quick as it is (it has never run out the back door like it really should).
Old 07-10-2006, 05:41 PM
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Here's my very academic opinion on your cam setup. Basically, it sounds like your cam is spec'd very well for naturally aspirated performance. When running a 300 shot, it's not going to be necessary to deviate from the intake valve closing point that you're using now. Basically, you can keep the same intake duration and ICL as before.

But because nitrous burns the charge so much faster, we need open the exhaust valve quite a bit earlier to cut pumping losses and retard the spark enough to keep our peak cylinder pressure occuring around 13-15 degrees ATDC.

Assuming 110 intake centerline, the current IVC is 62 degrees ABDC and current EVO is 64 degrees BBDC (at .050"). Common nitrous practice would recommend opening the exhaust valve about 10 degrees earlier for the 300 shot and backing timing about 8-9 degrees from what was optimal NA.

That said, a nitrous dedicated cam would look more like this:
264/276 113LSA +3
Same 62 degree IVC
New 74 degree EVO (now 10 degrees earlier)
2 degrees less overlap at .050"

Again, this is a very academic approach, but will get you in the 90% range of what is ideal. I'll leave getting you the last 10% to the experts and to track testing.
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2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
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Old 07-11-2006, 01:37 AM
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Originally Posted by Friendly Freddie
Erik , I will keep all of this in mind. Thanks for all of the usefull info. I hope we all learn somthing from this little experience of mine.

BTW, I have a progressive controler on the car. I leave on 10% of total power and ramp it to 100% over about 1.5 seconds. The car 60 fts 1.21's and 22's pretty consistantly on a good track. I have never had spark plug issues and A/F ratio is very conservative. I think fuel and N20 is divided pretty evenly because of the Carb style intake. I say this, because I don't think the tune is the issue here. I would'nt want to back it down any because the 60 ft is what makes the car a quick as it is (it has never run out the back door like it really should).
If you fix the cam you will see a lot more on the back half.
Old 07-11-2006, 11:47 AM
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Originally Posted by racer7088
If you fix the cam you will see a lot more on the back half.
That motor is probably having a problem blowing down the cylinder at rpm, and Id take 3 full points or so of compression out of it. Getting rid of cylinder pressure is your friend when lifting heads.

It doesnt take "huge" shots to justify having a "nitrous cam"

We have seen 50 hp gains playign with the cam on 200 shot setups even with pretty decently sized header primaries etc.
Old 07-11-2006, 01:15 PM
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Originally Posted by GrannySShifting
That motor is probably having a problem blowing down the cylinder at rpm, and Id take 3 full points or so of compression out of it. Getting rid of cylinder pressure is your friend when lifting heads.
It seems to me, that if you lower cylinder pressure, you will also lower hp and tq. I don't believe this is the answer he was looking for. He may just need heads with thicker decks or a more robust gasket setup (like o-ringing).
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2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.

Old 07-11-2006, 01:21 PM
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Originally Posted by Friendly Freddie
I REALLY wanted to drop this bomb in the "advs/disadv of rod length" thread , but I figured it might ruffle a few feathers by disrupting the present topic of conversation (although its changed about 4 or 5 times already ). Its hard to get really good information about this from true experts.

Moving on , I have a 358 inch LSX engine in my race car. It was originally assembled for use in the LS1tech series extreem mod class which was an all motor class. We kept it under 360 inches to get the wieght break. We soon found out that to get this little engine to 60ft , it needed so much converter that it was no longer efficient on the big end of the track. Faced with having to put a jerico(sp?) in the car or do something else with the engine, I gave up and put a plate system on the car and decided to have some fun. The camshaft was sourced from LSM , and ground specificly for NA use. Is there a possibility I will see a gains from a cam change if I get one targeted towards N20 use? If so, why? and what are the differences between an NA specific and a N20 specific cam.

I know N20 is a dirty word for "real engine builders". I also realize that this thread is kind of "self serving" , but there is not a whole lot of really good info out there on this topic. I think all of us N20 addicts would benifit greatly from a truely intellegent conversation on this subject.
Friendly Freddie's setup sounds alot like KECHME's old car.

Last edited by 1936FordPU; 07-11-2006 at 01:37 PM.
Old 07-11-2006, 01:34 PM
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What was the first clue?
Old 07-11-2006, 01:38 PM
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Originally Posted by Ben R
What was the first clue?
The motor. Then the origin of business. Whats up Ben. hehe
Old 07-11-2006, 02:15 PM
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Originally Posted by 1936FordPU
Friendly Freddie's setup sounds alot like KECHME's old car.
No coincidence.
https://ls1tech.com/forums/lsx-parts-sale/514695-complete-engine-set-up-sale-8-70-s-156mph.html
If the motor doesn't sell, I hope a nitrous-dedicated picks the car up enough to run lower 8s.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.

Old 07-11-2006, 02:18 PM
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Originally Posted by 1936FordPU
Friendly Freddie's setup sounds alot like KECHME's old car.
It's the same set up I've always had. 1936FordPU (aka V6bird), I thought you knew I was over here at Friendly.
Old 07-11-2006, 02:22 PM
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Originally Posted by Patrick G
It seems to me, that if you lower cylinder pressure, you will also lower hp and tq. I don't believe this is the answer he was looking for. He may just need heads with thicker decks or a more robust gasket setup (like o-ringing).
I am of the same opinion that lowering compression (by a large margin) will slow the car down.
Old 07-11-2006, 02:25 PM
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Originally Posted by Patrick G
Here's my very academic opinion on your cam setup. Basically, it sounds like your cam is spec'd very well for naturally aspirated performance. When running a 300 shot, it's not going to be necessary to deviate from the intake valve closing point that you're using now. Basically, you can keep the same intake duration and ICL as before.

But because nitrous burns the charge so much faster, we need open the exhaust valve quite a bit earlier to cut pumping losses and retard the spark enough to keep our peak cylinder pressure occuring around 13-15 degrees ATDC.

Assuming 110 intake centerline, the current IVC is 62 degrees ABDC and current EVO is 64 degrees BBDC (at .050"). Common nitrous practice would recommend opening the exhaust valve about 10 degrees earlier for the 300 shot and backing timing about 8-9 degrees from what was optimal NA.

That said, a nitrous dedicated cam would look more like this:
264/276 113LSA +3
Same 62 degree IVC
New 74 degree EVO (now 10 degrees earlier)
2 degrees less overlap at .050"

Again, this is a very academic approach, but will get you in the 90% range of what is ideal. I'll leave getting you the last 10% to the experts and to track testing.
Patrick, thank you for the info. I am going to get the ball rolling on this pretty quickly. I just have to find the time to get the car apart.
Old 07-11-2006, 03:18 PM
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Originally Posted by Friendly Freddie
It's the same set up I've always had. 1936FordPU (aka V6bird), I thought you knew I was over here at Friendly.
im just razzing ya. Im more excited you decided to keep the setup then going SBC. Ive thought at that myself actually lately to keep away from what you are experiencing at your power level. Im following the thread to see what comes of it.
Old 07-11-2006, 04:53 PM
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Originally Posted by racer7088
I can't tell you the hundreds of situations where a cam company promised people I know to pick them up and did not. I'm not saying that the problem was just the cam but I've seen one too many "cam gurus" in my lifetime already and most don't know a damn thing and I am NOT talking about anyone in particular because I actually like most of the "cam gurus" I know but I think you know what I mean! The guys from LSM and Camking are experts in their field of camshaft design and manufacturer and are NOT what I am talking about in general as well so I am not talking about them.

LS1Tech is quite simply the most cam obsessed and cam driven web site on the planet! People on this site have routinely told me how they could tell the "difference" between cams that were actually the same! I just don't say anything anymore.
Hey Erik...

Guess this is pretty much sums up what we were talking about the other day... Glad you said it, **** if I wrote this, I'd be banned!

Ed
Old 07-12-2006, 01:25 AM
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Originally Posted by Patrick G
It seems to me, that if you lower cylinder pressure, you will also lower hp and tq. I don't believe this is the answer he was looking for. He may just need heads with thicker decks or a more robust gasket setup (like o-ringing).
Patrick, no offense but you have to realize that NHRA Pro Stock only runs around 15.5 to one or so and they are not spraying (Well most aren't!). An engine with an only 26x at .050 cam doesn't usually run compression like that most of the time at least on gasoline and expect to spray a ton of NOS. Now if the car has crap heads or a restrictor maybe then it would work but it's just a lot of compression for a decent engine. Then you add a lot of NOS and you WILL probably detonate if God isn't your tuner. Dedicated NOS engines just don't run that kind of compression from what I've seen.

When I see the big boys running compression like that and cams anywhere near that I will let everyone know! Right now they are light years away from that and much lower compresion, at least the fast ones are.
Old 07-12-2006, 01:49 AM
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Originally Posted by Friendly Freddie
I am of the same opinion that lowering compression (by a large margin) will slow the car down.
Well you don't need it at 8 to 1 but I would say 12-13 to 1 is more common place. I did a small block chevy for a guy on LS1tech here that went low 8s and 170+mph right off the trailer and it wasn't anywhere near as radical as 15.5 to one! I don't think he was even spraying anymore NOS either.
Old 07-12-2006, 01:53 AM
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Originally Posted by EDC
Hey Erik...

Guess this is pretty much sums up what we were talking about the other day... Glad you said it, **** if I wrote this, I'd be banned!

Ed
Yes it is but I am encouraged that people are at least talking about all this stuff. The problem is that there are still guys telling people like Friendly Freddie that you can increase overlap and "bleed off compression!" This is the stuff that scares me and I hear stuff like that everday. People should know better. Even with all the cam talk on these boards though I just never stop hearing the crap like that.
Old 07-12-2006, 10:18 AM
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Originally Posted by racer7088
Yes it is but I am encouraged that people are at least talking about all this stuff. The problem is that there are still guys telling people like Friendly Freddie that you can increase overlap and "bleed off compression!" This is the stuff that scares me and I hear stuff like that everday. People should know better. Even with all the cam talk on these boards though I just never stop hearing the crap like that.
Erik, Bryan from LME just informed me that my compression is more like 14:1. I think I'll do something to back compression off just a touch.

I for one, really appreciate you guys that are "in the know" chiming in to help the rest of us out. I like to think I'm a pretty intelligent guy , but I don't know about a lot of the more complex things that are going on inside of a combustion chamber. I want to talk to people that are more versed in these areas and be able to make an informed decision. They say "jack of all trades, master of none" , I don't want to fall into that category.
Old 07-12-2006, 11:20 AM
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Originally Posted by Friendly Freddie
Erik, Bryan from LME just informed me that my compression is more like 14:1. I think I'll do something to back compression off just a touch.

I for one, really appreciate you guys that are "in the know" chiming in to help the rest of us out. I like to think I'm a pretty intelligent guy , but I don't know about a lot of the more complex things that are going on inside of a combustion chamber. I want to talk to people that are more versed in these areas and be able to make an informed decision. They say "jack of all trades, master of none" , I don't want to fall into that category.
Well even 14 to 1 sounds a lot better and I know you were set up for NA at first. 15.5 to 1 is usually pretty damn hard to get anyway! at 14 to 1 you aren't way out of range at least. The NOS will make a little more power with high compresion as well but most experienced NOS guys get leery of super high compression and big NOS since it's starting to get unstable at those compressions to tune so usually they have to back off the tune quite a bit for safety.
Old 07-12-2006, 11:24 AM
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Ha, love it. Sort of reminds me of a discussion I had back in the day on this
forum about Nitrous and relatively low compression on pump gas.

Nice to know someone knows better!

Last edited by Adrenaline_Z; 07-12-2006 at 11:41 AM.


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