I have a few questions about how high TPI can rev (before it can't feed anymore) that is keeping me from deciding on a cam:
1. How high can a TPI with a siamesed base/runners and ported plenum go?
2.Then going by ONLY that factor, what would be the optimum LSA and Duration @.050 (generally speaking)
I had done some research in the archives and found a dyno by madmax(?) but it was only a siamesed base.

 

One of the best ways is to get TPIS' Insider Hints book. It shows a lot of dyno graphs using the stock setup as well as comparing that setup to other TPI intake setups and with different camshafts with different durations and Lobe Separation Angles.

As far as how high it will still pull? I've had mine up to 6375 rpms in second gear (that's as high as Diacom would report) and the engine was pulling so hard I couldn't really tell when there was a fall off. I know there was one, long before that rpm, but I just couldn't feel it. I'd need a dyno graph to really see.

So like most things, it will depend on the combination of parts you select; 1.1, perhaps even 1.2 HP per CI if complimentary parts are used.

My thinking that high RPM horsepower isn't the way to go for a street engine, it's maximizing torque in the low and midrange rpm band.

If you want to sing the engine up high and STILL make more HP up there, the TPI isn't the way to go.

Maybe some of the guys will post a dyno graph of a stock and a modified TPI graph for you.

Hope this helps.

Jake

 

Jake jr,
I was not planning on building a high reving engine. I was wondering just how high my limit was so I would not purchase something that would not work good by putting power too high. Where can I find this TPIS' Insider Hints book? Thanks.

 

Oh. Just call comp cams and ask thier opinion (it's a damn good opinion). Tell them you have a stock TPI setup. If you are planning to siamese the base, tell them you have an aftermarket base.

A stock tpi with upper and lower plenum port work will make power all the way to about 5500, and when it falls it won't fall near as badly as an untouched TPI.

My opinion, and I don't work for comp cams , would be to get a cam that makes power from 1500 to 5500rpm.

 

http://www.tpis.com is the site and should have info on ordering their catalog and the Insider Hints book. The Hints book is loaded with tuned port info and well worth the small cost; you'll learn a lot about the tuned port engine from reading the book, even if you don't ever buy any of the parts they sell.

After almost 40 years of screwing on nothing but carbureted engines, it's how I began to learn about the particular requirements of the TPI engine.

Jake

 

Thanks. I'll try both of your suggestions.

 

What parts are you going to run? Stock or aftermarket stuff?

 

Stock intake, rails, plenum. Aftermarket runners, fuel pump, throttle body and injectors.

 

What runners? How heavy do you plan to port the base?

All this matters, alot.

 

Slp runners totally siamesed. siamesed base in about 3 inches.

 

Keep your cam intake duration @ .050 under 230; get as much valve lift as you can and opt for aggressive ramps on the lobes.

Keep your head intake port volume at 200 ccs or under.

Jake

 

Thanks for all the replies. I have called, looked for, and found a couple of cams that match up with what you guys have recomended and that go along with the rest of the engine. I might have a problem with the amount of lift I can run. The Worlds have a maximum lift of ".560". However I am going to stroke the engine so I am trying to get a hold of Speed-o-Motive to find out if there stroker kit will change my maximum valve lift as this will dictate the amount of lift I can ultimately run. The cams that I am looking at now are as follows:

211/219 .530/.560 112 Lingenfelter
213/219 .493/.502 112 Lingenfelter
210/220 .533/.544 114 LT1
218/228 .560/.560 112 LT4
212/226 .554/.554 112 TPIS
208/221 .505/.544 112 ZZ4
213/221 .538/.560 114 Crowler
212/218 .520/.528 112 Comp
218/224 .528/.536 112 Comp

All the duration is measured at .050 and the lft is measured in the 1.6 ratio rocker arm I will be running.

 

maybe im misunderstanding something here.... but the stock LT1 cam has no where near that much lift, and i have an LT4 cam, and with 1.6 rockers its .476/.480 lift... even the LT4 hot cam is only .525/.525.... and if i remember right the zz4 cam is something like .480/.510, and as far as stroking the motor the only way that will effect your maximum valve lift is if you run pistons with a big dome where the valve would hit the piston, and my understanding is that this usually isn't a problem in a street bound sbc

 

Maybe I was misunderstanding something than. I thought that the GM cams were measuered at a 1.5 ratio rocker arm, so I calculated them out to the 1.6 ratio that I was going to use. I'll double check but thanks for pointing that out to me. The LT4 cam that I posted was the "hot" cam and there is more than one LT1 cam. How did your LT4 cam work out for you? Thanks.

 

ZZ4 208/221 .474/.510 lift 112 LSA w/ 1.5 RR

 

Both the lift and duration #s of the Hotcam is rated by GM at a 1.6 rocker ratio.

All the other cams you listed are rated at a 1.5 rocker ratio by the manufacturer.

I like the Comp XE Cams, for LTR the 218/224 cam would be a real nice match. Might even want to try and run it on a 110lsa, they have that version as an off the shelf grind.

So your #s on the Hotcam lift are wrong, as listed above.

It is also important to note that duration grows slightly also when you run a 1.6 or 1.7 rocker ratio. Figure on about a couple degrees per ratio increase.

 

food for thought, the GM cams will be cheaper than the others. ZZ4's can be had for around $100-$120 I'm pretty sure the LT1 cam doesn't have that much duration either.

 

A 212/218 and a 218/224 are in the ball park of what you'd want.

There should be about a 500 RPM difference of when the engine comes on the cam, the 212/218 500 RPMS earlier than the 218/224.

There are a lot, I mean a LOT, of cams that have those specs (212/218 and 218/224); what you want is the one with the most aggressive ramps to give you the maximum area under the curve.

When comparing two cams that have the same advertised duration measured at the same lifter rise (usually .006 but you'll have to check to be sure), subtract the .050 duration from the advertised duration. Assuming lifts are about the same, the lower the difference, the faster (more aggressive) the ramps.

Example:

276 Adv 218@.050=58
274 Adv 218@.050=56

The second cam has the more aggressive ramps. Just make sure all the cams have their advertised duration measured at the same lifter rise AND the valve lifts are comparable.

Be careful when comparing cams from two different cam companies because not all companies measure their advertised duration the same way. Mechanical cams and hydraulics are measured differently too. Some mechanicals are measured at .015, others .020, etc.

Jake

 

The Comp XE lobes are very agressive, you can see it just by looking at them.

I have an XE in my motor and we are sticking an XE in my buddys motor.

The cam is at his house, next time I am there I will get pics of the XE cam next to the L98 cam next to a flat tappet cam.

Scroll all the way down to the bottom of this link, you can view some technical info on cam lobes.
http://www.compcams.com/Technical/Products/Camshafts/

 

280/270 211/219 69/51 .530/.560 112 Lingenfelter #74211
213/219 .493/.502 112 Lingenfelter #74216
210/220 .500/.510 114 LT1 12551705
218/228 .525/.525 112 LT4 24502586
282/287 212/226 70/61 .554/.554 112 TPIS #700-118 ZZ-9X
308/316 208/221 100/95 .505/.544 112 ZZ4 #GMC-101850071
264/273 213/221 51/52 .538/.560 114 Crowler #00482LM
264/269 212/218 52/51 .520/.528 112 Comp #08-501-8 XR264
269/276 218/224 57/58 .528/.536 112 Comp #08-502-8 XR269
276/281 224/234 52/47 .536/.544 112 Comp #08-503-8
210/220 266/276 56/56 .533/.544 112 Comp #08-304-8 CS 266H-R14

These are the new numbers calculated and re-calculated. The advertised duration is first, then measured at .050, then how aggresive the ramps are, lift with a 1.6 ratio LCA and a part number. I have the ZZ4 and LT1 and LT4 at the right lifts now. I did call the manufacturers up again and they suggested what you all had me looking at. It looks like I will either go with the ZZ4 or the TPIS cam. Maybe the 218/224 comp cam. The ZZ4 is the cheapest and I have heard only good things about it. Does anyone know who is running a TPIS cam? I almost think that it would be nice if someone took alot of cams (with good member reviews) and put them on a list like this. Maybe a Technical artical section on good cams for _, _ or _? Thanks for all the help.

 

Here's my personal experience with the ZZ9.

I bought one and took it to Dennis Wells' Racing to have it checked on his Cam Pro Plus computerized camshaft checker.

Dennis is one of the most well respected small block engine builders in the DFW area and regularly writes technical articles for and is featured in dirt track magazines.

He's the first guy I know of to write about running hot water through the engine block during the honing process to account for the heat of a running engine in order to get a rounder bore and a better ring seal.

The intake LSA checked at 112.6, and at .050 was 110.4. So if you use the lobe centerline method of degreeing, at .050 the cam would need to be retarded 2.2 degrees to install it straight up.

The exhaust LSA checked at 112.6 also, and at .050 was 113.1

At .006 the intake checked at 264.3 degrees
At .006 the exhaust duration checked at 276.4 degrees

The advertised duration for the intake @ .050 is 212; it checked 208.2

The exhaust duration checked at 223.5 @.006 - I believe the advertised exhaust duration is 224 degrees.

I have the entire computer printout I can email if anyone's interested.

Draw your own conclusions.

Jake

 

Jake,
That's pretty in depth, but if I draw my own conclusion from that I would say that the GM cams were not the best. I was re-thinking again and I might now go with Crowler or 212/218 comp cam. That is a surprising story of how much a cam can be off.

The only bad stories that I had heard about cams is when a certain cam lobe would wear down faster because the material would be of different consistincy. When you compare the aggresiveness of the different cams ramps it really does help in choosing a camshaft. It is easy to tell then how much different they will be as well as perform.

Ominious,
I checked out that page/link in your reply and it help out a little bit in choosing between their cams. I just didi not like the fact that the duration and lift was the same on the intake and exhaust valves. I have always thought that since the intake valve was bigger you would need a longer duration and lift. If I was way off, tell me other wise. Those cams did have really nice numbers. The ramps were pretty agressive. I was not too excited about the LSA #s at 110. Seems like I would not be able to get much low end out of the TPI set-up with one of those and it would make it breath better at higher RPM's where TPI doesn't have much left. So why did you like that series so much? I perfered th ER series.

Thanks.

 

TIBO, THE ZZ9 CAM IS NOT FROM GM, BUT FROM T.P.I.S. THE TPIS ZZ9 CAM IS BASED OFF OF THE GM ZZ3 CAM. IF YOU PURCHASE THE GM ZZ4 CAM, YOU'LL BE IN PRETTY GOOD SHAPE. THINK OF IT THIS WAY, TPIS CLAIMS AN IMPROVEMENT OF AROUND 17 HP WITH THE ZZ9 OVER THE ZZ3. THE ZZ4 CRATE IS RATED ABOUT 20 HP OVER THE ZZ3 (355HP, 335HP). THE BIGGEST DIFFERENCE BETWEEN THE ZZ4 AND ZZ9 IS PRICE.... THE ZZ9 WILL COST YOU ABOUT $250 MORE THAN A ZZ4 CAM.

BTW, FOR THOSE WHO ARE OFFENDED BY MY CAPS, I'M AT WORK AND MY KEYBOARD IS LOCKED FOR UNIFORMITY, SO GET OVER IT, LOL.

 

soooo if I figure out the ramp rate on a ZZ4 cam

what is the advertised duration ?

I know the 208/221 @.050

 

D's89IROCZ,
If you want all the specs onthe ZZ4 cam then you should scroll up, I posted them a few days ago.

gixxer9,
I had always thought that the ZZ4 and ZZ3 cams were the same? I have had several people tell me that the ZZ4 cam would work and will work with out prom changes. It does however have the least aggressive ramp rates, by far. Onimous and Jake Jr have pretty much got me sold on a Crowler or Comp cam that had been talked about. I don't think those cams would be overkill. After hearing Jake Jr.'s experience with the ZZ9 cam, I don't think that I will buy it. Thanks.

 

Tibo, I am not using the ZZ4 cam or a TPIS cam. I'm using a Comp Cams solid roller, personally. I was just pointing out that the lack of quality on the ZZ9 cam should not reflect onto GM for their ZZ series cams. Two different companies with different cams.... BTW, it's Crower, not Crowler.

 

Dude, If your going to keep the LTR set up go with the lingenfelter 219/219 cam. Will make the best power and is still streetable. Lingenfelter is clearancing these cams for $250 on there website. That's where I got mine. I sold my zz-4 cam, it just isn't made to work with the LTRs. do a search, I had a real good thread going on picking cams a month or two ago.

 

From what I've read, the SB Chevy's exhaust port has, in the past, been extremey deficient. One way to address that problem, without having the heads custom ported, was to offer split duration camshafts. (not to mention headers, free flowing CATs and mufflers, true duals, etc.)

Remember, it's air/fuel in, combusted and exhaust out that determines the ultimate power of out "air pumps", so a less than efficient exhaust hurts power production. Especially as the RPMs climb since there's less time for the exhaust to exit.

Sort of like a whale that can expel 90+% of it's used up air while we humans can only expel about half that much: the whale can stay underwater longer, in part, because it can intake a greater amount of usable air. There's more to it than that, but I think you get the idea.

Now, when you factor in that the engine's exhaust has to flow through stock exhaust systems that are very restrictive (meeting emissions requirements, sound control, cost, etc.) the need for a split duration cam becomes even more evident.

I suspect that most performance factory cams are split duration these days. Of course, if you're running aftermarket or ported heads, then this requirement a split duration camshaft may change.

In comparing camshafts for the aggressiveness of their ramps, don't forget that the advertised duration (for all the cams being compared) has to be measured at the same lifter rise. Apples to apples.

You may, on occasion, find a camshaft that has what appears to be "killer" ramps, but take a look at the valve lift it offers. If the valve lift is low, scratch that one from your list.

Jake

 

they are the wrong specs ...and you DIDN'T post adverstised duration
your lift was wrong

.474/.510


....after reading this all I want to buy a LPE cam now !

 

D's89IROCZ,
Those are the right specs. I calculated the lift at a 1.6 ratio rocker. They give the lift measured at 1.5, not 1.6 so I re-calculated it and it comes out to that. To calculate 1.6 lift from a 1.5 arm you:
1. Divide the 1.5 lift by 1.5
2. Take that answer and then multiply by 1.6
You then come up with .505/.544

If you had read the whole post you would have known that. That is advertised duration and duration at .050. I got them from a GM catalog the first time and the second time it was brought up I actually called GM and asked them for them. If you would like I can get the cam card from my science profesor and fax you a copy. I am trying to learn stuff here, so please try not to belittle or nit-pick, because I want to learn stuff, not get mad.

Gixxer9
BTW, it's Crower, not Crowler. Now you tell me I have been spelling it wrong after I wrote it like fifty times in the last week.

Thanks again Jake-you know too much.