I want it to run its max. Its a drag car....

So this would be an issue when getting a custom grind cam? As in something would need to be done to get more power or the LT intake cam would just move my power to a higher rpm?

 

If you keep your LTx cam and swap to a Victor intake, you'll probably gain around 15 hp and it'll move the peak up by about 500 rpm, depending on the rest of the combo.

I think you should put IVC somewhere around 46 deg ABDC, maybe later depending on converter stall.

Mike

 

5° @ .050" hmmmm

GM847 = 14°
CC306 = 13°

MS3 = 13.5°
TRex = 25°
G5X3 = 14°

All popular cams that are well over 5°. I agree less can make the car more liveable but it's far from the only player in that game.

As for the IVO it depends on what works best. In the case of something like your favorite the TRex, 13 IVO is stupidly wrong in a RPM range that is used in any street car.

Bret

PS as for the arguement with everything, I just honestly don't think you see the forrest for the trees and you miss a lot of details trying to give a catch all answer that in reality is honestly impossible to answer definately.

 

How can you even give a general IVC with what info is given? Professionally I don't agree, and not knowing the compression, gear, max RPM, stall and vehicle mass you can't even get close.

Does a cam change due to the intake swap? Yep. Does everything else come into play? Yep. Could you run a later ICL with a single plane over a LT intake? Yep. Would you always? Nope.

Again I don't think there are hard fast rules to anything here. I don't want to say it's magic, because it's not but so many things come into play that a 400rpm change in RPM band etc... can change the optimum valve events.

Bret

 

Okay, I had an 847 in my last car. I thought the idle was too rough for a true street car. My current cam has 2 deg overlap and it's borderline for my taste.

All I can say is that lots of different IVO's were tried on that cam and the production version is what accomplished the goals. With the cam-only LS1 record, it's hard to argue with.

I noticed you avoided my question. Have you ever seen a power improvement from moving the IVC later than 6.5 deg BTDC?

Mike

 

You might want to say it that way the first time before you accuse someone of ignoring you.

Either way it's not just one valve event, and would you be starting at say 14 BTDC? Dumb question to just abitralily say that to entice a "discussion".

BUT to answer the question, yes I have seen that and in fact the cam would go in a LS1 and walk all over a TRex BTDT.

Oh yeah I forgot that the "cam only" super duper LS1tech record was something to brag about, mythical internet racing classes always are.

Bret

 

The TRex cam was specifically designed to give the maximum power possible when using stock or near-stock heads, intake, compression ratio, and cid. So, yes, it does what it was designed to do quite well. When your cam "walks all over the TRex" in these conditions, I'd like to see it. 450 rwhp and low 10's at 130+ with bone stock heads, intake, and bottom end won't be easy to "walk all over".

Mike

 

Either way Mike think what you want. Besides I don't consider a shop car getting good numbers worth much these days in LS1 land either on the dyno or track, what really matters is what customers miles and miles away get with the same parts. The "shop car" of today is a suckers bet to mindless consumers who follow the rest of the lemmings into the trick of the week.

The point here was that yes it's possible to make the same peak HP values (and make more average power thru the RPM range) with much later IVO and in fact have it earlier than 6.5° BTDC.

My point is that IF you do things correctly, and that means not moving the IVO too early you can have a larger difference in pressure between the intake port and cylinder when the piston moves away from TDC. This also tends to make the motor stronger in a wider RPM range. The problem is you can't get stuck in the stale thinking of "there is a certain split that is needed" or "we have to maintain a LSA of 112-114" blah blah. It goes much, much deeper than that and the only guy who I have ever, EVER, EVER even hear mention this was a R&D Engineer at GM Racing. Almost NOBODY talks about motors in terms of their pressure differences, but in reality that is all that counts. CFM, Velocity, LSA, Duration etc.... are all small players in comparison.

Bret

 

The car that made 450 rwhp stock long block was a shop car. However, the one that ran low 10's at 130+ was an ordinary customer like everyone else. His dyno pulls actually didn't get quite as much power.

I'm just curious. . . the cam that will "walk all over the TRex". How much power will it make? In order to "walk all over" a 450 rwhp setup, you'd have to be making 480 or better with a stock long block. Has this been done? If so, I'm sure a whole lot of people would be really interested. . .

No kidding. . . but everytime I point that out, you pop in and say that you can't look at individual valve timing events either without doing some Computational Fluid Dynamics and modelling each events' effect on the others, think about the effects of the Reynolds number, and blah blah. . . oh crap, save yourself some effort, don't bother trying to learn this stuff, and just buy a cam from me.

Mike

 

People can be interested all they want, I'm not into advertising and putting funny names on things unless the customer names them. FWIW a customer wanted his LS7 cam from me to be the "Chuck Norris" cam and the heads are "Bruce Lee" heads, it's what he wanted. Besides, racing a cam only LS1 car is about as stupid petty racing as you can get. If you want to impress me go build a car for a class and win it, I hear there is a real LS race in Memphis later this year.

Mike, I've come to the conclusion that you don't get it. Period. (See My Signature and then see yours) This isin't "Computational Fluid Dynamics" or "the effects of the Reynolds number" which don't play into this at all, but then again YOU DON'T GET IT ANYWAYS!

I'm not here hyping the new trick of the week, so you don't feel you can get anything from me. The reason is there is no new trick of the week other than LEARNING and hard work, seems you don't like doing any of that. I've already wasted enough time talking about this with you I'm not going to waste more to upload graphs and then try and explain something to you that very few people actually understand when I do show it to them in person. Frankly in the end, 1. I don't think you got the marbles to get it, 2. It's too much actual work to get anything out of it if you wanted to use it, and if you wanted all the forumulas and software to get the answers then go spend $1000 on it and buy it!

Then again my old man reminds me that I don't just post on here to explain things to the few choice morons, I explain things to the people who don't run their mouth to get attention and that really want to learn something.

So here is a simple REAL WORLD example of a setup I helped a engine builder who was building motors for Professional Competition (Multi-Million Dollar Sponsors) improve on what they had. My predictions of average power/TQ and peak values where verified and almost exactly shown on the engine dyno. (within 1.0hp) The cam I gave them made the most peak TQ, most average HP & TQ and the same peak HP that they have EVER MADE, and this was a well built and tweaked motor combination.

See PIC http://usera.imagecave.com/sstrokera...estExample.jpg

The data being displayed in the upper left of that picture is of what is happening at TDC. What you will notice is that there is a .7psi larger difference (+63.6%) from the orginal cam to my design, and this is just at peak HP RPM. You will also see that the IVO is LATER than with the old cam (2.5°). Reguardless who cares about the valve events, the pressure differences are key here, and the only big difference is at TDC. What really gets interesting is all the data at RPM points where there is a much larger difference in TQ/HP output, but this is a simple explaination.

Either way that's enough out of me for this thread.

Bret

 

Boy you should sit in/hear MY car....dude if you thought that 847 was too much for a streetcar.......WOW you should hear mine.


That beotch ROCKS DA HOUSE 'YO!!!


Bret any idea how much overlap mine has? It is your cam. I know, I CAN figure it out...but you KNOW I am lazy he he.


David

PS Bret I don't get it either....but I get some of it...vids coming soon.

 

What do you use to log that kind of data?

 

Stupid or not, it's what people want and it's what people buy. I, personally, have never wanted to build a cam-only car, but there are plenty that do.

If you think you can build a 900 - 1000 hp naturally aspirated motor that will run on pump gas, and do it for less than $20k using all new parts, and have it idle smooth and require no more maintenance than my stock pickup, then I challenge you to. I can and have built a couple of those. You can't do it without forced induction.

I never said that. In fact, every time I ask you a specific question, you say I need to buy my own dyno, flow bench, etc. . . and figure out for myself.


Here we go with the personal attacks again. . . must you always resort to that???

I'm surprised you finally posted some real numbers. A couple questions. . . what is so different about that particular engine that required the later IVO (of course, it looks like about 25 deg BTDC, which isn't that early)? Runner length? Plenum volume?

Also, predicting with 1 hp? All the engine (and chassis) dyno testing that I've done had a standard deviation well over 1 hp.

Oh yeah, and just how bad would your cam "walk all over the TRex" again? We talkin' like 5 hp? 30 hp?

Mike

 

This is going downhill fast..... and is about to be closed. Stick to the technical issues. Name calling and personal attacks are not productive.

 

You have over 15° @ .050" just on the exhaust side!!!!

38° Total @ .050", Hey you wanted all that power and 10" of idle vac, which is right where you should be.

Nothing you wouldn't find in any other long runner street motor like a LS motor, Mod motor hell anything OEM today. Almost everything made today works in the 3rd and 4th harmonic wave.

Induction length is 15"+ total

Plenum Volume is 200cubes+

Yes it has a early IVO, but it's a RACE MOTOR!

1. You need to start working with better equipment.

2. Once you model the motor you are starting from accurately you can get things this close. There is as much time in getting accurate info to base everything on as there is doing the work to get the new designs.

You don't have to believe it but none of that **** is made up. I can't say every specific otherwise I would be giving out too much info.

I don't mean to pick on you but you really need to start looking outside of your box to find the answers you are looking for.

If you want to setup motors to get this actual data the heads and headers need to be setup with pressure transducers, which run around $500K+, only place I know that has them is GM. Thank god for software and lots of good formulas to get you a accurate model of it without all that money invested.

Is there more in the cam on that motor in the example? MAYBE, but there are many other barriers to power that would have to be overcome first.

Bret