Using Dyno2000 I have finally made what I see as a near perfect model of my engine, every single possible specification has been entered and is correct and has been double and tripple checked!

Anyway, I did this to find out what cam would give me the best gain in terms of HP and TQ. It turned out to be the LT4 "HOT" cam.

Here are the results I got:

LT1 Cam: No Improvement

LT4 Cam: No Improvement

L98 Cam: 242HP@4000RPM / 338FT/LB@3000RPM (Perfectly smooth TQ curve)

ZZ3 Cam: 264HP@4500RPM / 327FT/LB@3500RPM (Not so smooth TQ curve)

LT4 "HOT": 264HP@4500RPM / 330FT/LB@3500RPM (Perfectly smooth TQ curve)

ZZ4 Cam: 267HP@5000RPM / 316FT/LB@4000RPM (Not a very steady TQ curve)


The LT4 "HOT" cam gave me the next to best HP gain while mantaining a fair amount of TQ so that is my final choice for my camshaft swap.

Finally my question; All of the work I did was based on what I believe to be 1.5 rockers (when I looked up the cam specs it was all based on 1.5 rockers). What would happen if I went to 1.6 during the swap? Would that be overkill? Should I just stay with my factory 1.5's and just upgrade the valve springs?

I ask because I want to buy this exact kit:
http://www.gmpartsdirect.com/perform...CATID=826.html

It's only $475.30 !!!

Thanks!

 

How did you get 2 different power curves when both those cams are exactly the same?

 

I think maybe your Dyno2K program is a little screwy. You should have realized some gains with the LT1/4 cam over the stock grind. Nearly everyone in the real world does. And the apparent differences you got with the ZZ3 and LT4"Hot" cam, and the fact that L98 cam does better than the LT4 is just wrong.

 

Here are specs I found an used:

LT1: 205/207 Dur, .451/.450 Lift 117 LSA
LT4: 203/210 Dur, .476/.480 Lift 115 LSA
L98: 202/207 Dur, .413/.428 Lift 114.5 LSA
ZZ3: 275/280 Dur, .474/.510 Lift 114.8 LSA
LT4 HOT: 218/228 Dur, .525/.525 Lift 112 LSA
ZZ4: 225/240 Dur, .525/.558 Lift 116 LSA


The LT1, LT4, and LT4 HOT cams are the one's I had to search for an make. The L98, ZZ3, and ZZ4 cams there were premade files for.

Are all of those specs correct? What are the exact corrections?

Thanks!

 

Here is my engine file, would you guys please check it for accuracy:

 

Well I did a more detailed search on the ZZ4 cam specs to see for my self rather than trust the ready made file and it turns out the ready made file was wrong!

The ZZ4 cam specs are:

208/221 Dur, .474/.510 Lift 112 LSA

Which also means my ZZ3 cam file is wrong since they are both the same cam.

Now using the correct ZZ4 numbers I get:

268HP@5000RPM / 333FT/LB@3500RPM

So if that is correct then the ZZ4 cam is by far the best choice for my engine....

All my other cam specs were correct so I guess I'll get a ZZ4 cam instead of an LT4 HOT cam...

 

Never mind, after reading through posts about the ZZ4 cam it won't work on my 305 without atleast 9.6:1 compression and a custom chip along with allot of other expensive parts. Since the LT1 or LT4 cam didn't give me any good results I'll just stick with what I have.

 

The LT1 cam gives good results to everyone who uses it on a 305. It should show a good gain for you, at least 20 hp or so. And you won't require valve spring work or anything else on the heads.

 

20+HP huh? What about loss in TQ, how much is that? I definantly want new valve springs anyway because my valves start to float before redline. So if I do an LT1 swap I'll get new valve springs...

 

How much power are you looking to make? I have down quite well with simple bolt ons... check my signature!

 

I have about 237HP and 364FT/LB right now and I'd like to get about 270HP with a loss of no more than 30 FT/LB's with a cam swap. I don't mind going to 1.6 rockers and I plan on upgrading my springs accordingly. What cam would you suggest?

 

Ahhh, that is called "Eating your cake and wanting to have it, too."

305s are hopeless in that instance. If you add a cam with more lift and duration, you will always lose a bit of low rpm torque, period. 350s can cope better due to their extra 45 ci, but 305s will show it.

Only remedy is steeper rear gears or a higher stall torque converter.

 

Well then I'm covered because I'm installing 3.42's next week and getting a new stall converter when I rebuild my tranny this spring

 

Excellent!

So, the LT1 cam is the one for you

 

Alright then, I'll take your word on it and when it comes time for my cam swap I'll use the LT1 cam. Remember, I know where to find you

 

Yes you do!

Have you ported and polished those 305 heads yet???

Follow the link at the end of my sig for another 30 hp or so

 

No because I don't personally feel like it's worth my time to do all that to stock heads when I can just buy WAY better aftermakert one's but I might consider it one day who knows...

*** DAMN Dyno2000 is pissing me off!!!! No matter what, the LT1 cam give me less HP and TQ than my stock LB9 and I know I have ALL of the specs 100% right on, damn Dyno2000...

 

OK, the problem is that you are assigning the cam a "duration at 0.50" in the Cam Specs section, when DD2000 is designed to work with "Seat to Seat" specs.

I substituted the Crane Energizer 280 cam for the LT1 cam. It has the same lift and other specs are similar, but it is not a roller like the LT1. Add maybe another 5 to 10 hp arriving about 500 rpm earlier, to correctly imagine the LT1 cam.

Also, I think a TPI setup will more correctly flow about 600 cfm, so I corrected that, too.

Once you add a set of heads, this 305 will rock!

By the way, the home ported 305 heads only cost $400 US and flow like Vortecs. But if you insist on spending more money ...

 

Alright but where the hell do I get seat-to-seats specs on all the cams so I can mess with them and what are the seat-to-seats specs on my factory LB9 cam??? I thought Dyno2000 was fine with normal specs as long as you tell it that it is speced at .050 ?

Also how much would it cost me to send my factory heads off to be worked?

 

Have you gotten the latest DD2000 update file? That may be part of the problem. DD2000's own instruction book tell you that they use "Seat to Seat" specs for all their included files. Some folks, when building their own, don't specify that. A dead giveaway is when you get the graphs and the torque curve is a line simply descending across the rpm scale. It should be relatively flat, or ascending and descending gently until the 5200 rpm mark, where it MUST intersect the hp line.

The LB9 cam is just the notorious "Peanut cam" designed as a roller. Terrible performance past 3500 rpm

You do your own work on the 305 heads to get them flowing. If you have to get someone else to do it, it won't be economically feasible. However, F-Bird'88 does these heads as a complete setup--ported, polished, bowl-blended and larger valves, springs, retainers, etc.--for less than $400 US + shipping. If he has a set sitting around you might talk him into it.

 

Dude, run the XR276HR, now those results are what I'm talking about! 281HP@5000RPM / 330FT/LB@4000RPM

There is one on eBay right now with only 3K miles and matching springs, I might buy it.

No I don't have any update file because I have 3.08 and the 3.10 update won't work for some reason, it says it doesn't like my Dyno2000.exe file.

 

OK, here it is. However, this cam has a LOT of lift and duration. You will HAVE to have the spring seats ground down to accomodate that, and it costs extra. With stock height valve springs the most lift you should attempt is in the .45x region.

And this will definitely hurt you low rpm power. I think it is just too much unless you are running a 3000 rpm torque converter and that is a bit much on the street.

Then again, roller cams are a different kettle of fish because they open the valve soon, lift it higher and close it quicker. The duration may not be a factor.

Where are you planning on driving this car? Is it a drag only car?

 

It's a street car, not a drag car. I just want around 325HP out of my 305 eventually and I have allot more mods to go. I need to be CA legal too. Oh and that 325HP goal, I expect that to be when I have eventually full rebuilt my motor and bumped it up to 10:1 compression and have all my other mods done.

So if I got the XR276HR, when I did my head work I could have the heads done to work with the new cam then right? I don't want anymore than a 2500 RPM torque converter.

See now the lift confuses me! I know I should use anything more than a .450 or so at .050 in my stock engine the way it is but the measurements in Dyno2000 for XR276HR are seat-to-seat on that cam right, not at .050 so wouldn't that be ok in my stock engine or am I looking at it backwards?

 

It is the duration that is measured at seat to seat or 0.50 lift, not the lift.

Roller cams act a lot quicker than flat tappet cams, though, so you might be OK power-wise. It is the long duration at low rpms that lets the exhaust start to flow backwards and re-enter the combustion chamber, thus contaminating the fresh fuel/air mix. That kills power and is all that the lumpy cam's "rumpity-rump" means.

The general rule of thumb is that one hp/ci is easily achievable and runs nicely on the street. As you go past that point, you have to start using more gearing, looser torque converters, etc., just to accomodate the cam. A roller, as I said, lets you go further and still remain a nice driver. But it will definitely require aftermarket heads or the machining of the valve seats to allow its greater lift.

Hope this is understandable

 

Got it, thanks for the clarification.

 

Have you read the Chevy High Performance mag's "My Generation Camaro" series? They did up a 1987 Camaro with a 305. To meet California emmisions they had to limit their roller cam choice to the .42x region. It was carbed, however, so you might be able to get around it with a custom burned chip for the fuel injection's computer.

 

I read that but according to CA law it's doesn't really matter what the cams specs are as long as you pass on the smog dyno and it doesn't have a big lobe to it when ideling. It can still sound mean but if you pass the snifer it's not like they are tear your motor down to spec your cam. I was told this by several smog shop owners...

 

OK. I live in a province that has no smog laws so I'm rather uninformed on that problem.

Check with the guys on the TPI board. They might be able to help you out with the XR276 cam questions. I would imagine that in adition to the spring seat mods, you would also have to have the prom chip reprogrammed. I all likelihood soneone there has already done this and can tell you how to iron out all the wrinkles.

 

Alright I will, thanks for all your help!

Alex

 

No problemo, compadre!

Be sure to let me know how it works out

 

I just made this post in the TPI forum:

https://www.thirdgen.org/techbb2/sho...hreadid=152417

 

That ought to get a response tailored to your needs.

 

I sure hope so. I heading over there right now to post the cams specs too...

 

DD2K has some problems... its a good software... and acurate at times... but definatly not as accurate as Engine Analyzer... i put the exact same engine in on DD2k and got 30 Less hp than when i put it in EA... the think that DD2k doesn't account for is ramp rates and other cam specs etc...

 

They were supposed to have fixed those problems in v3.10 but it doesn't matter to me because I'm using Dyno2003 now...

I wish I had EA but no way I could afford it

 

only way i can use it is through a friend of mine who has it...

 

You should download the new Dyno2003 demo and try it, IMO it freakin rocks compared to the cheesy Dyno2000. Try it and then tell me EA is that much better...

 

Where is it?

 

http://www.motionsoftware.com/dyno2003prodpage.htm

The link for the demo is towards the top of the page, right in the middle of your screen when the page first loads.

 

I like virtual 4-stroke better. Although DD2000 has given me a pretty good idea as of where my peak Vol eff should be and the general slope is similar, still it's far enough off that it makes pretty bad claims. Who's to say shorty small tube headers with blowmasters will flow the same as a nice set of full length small tube headers with straight through race mufflers. Or tri-y headers, etc. The only way to simulate it is to use virtual 4-stroke. It's one of the best engine simulation software packages. It takes a little longer to design and setup but the results are that much better.