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as some of u may know from my other threads on here, my car is being redone, and im going procharger when everything else gets done. so on to the question, how would my combo work with a lti cam 1.6rr's and plenum and runner porting work.. would it be woth it.. i dont want to go into the heads, because if this motor does blow, there will be a nice crate going in its place. other mods will include all umi suspension and a built 700r4 with about 2400 stall. see sig for other mods. thanx in advance to all u cam pro's...
Well, lets start with what cam is in there now, assuming it's stock. There's been PLENTY of threads about what TPI motors had what cam and I think that subject is pretty well understood by many on this board by now.
Long and the short of it is that the earlier MAF 305 TPI engines backed by an automatic trans had the "peanut cam" with VERY modest lift and duration. One of the smallest cams GM ever put in an V8, if not the smallest.
Long way around the barn to say that in your case, an upgrade to an LT1 cam would be a big step up from what you've got now, even though it's not really all that "big" by performance standards. Compared to the "peanut cam" it's a fire-breather. It's also got a pretty wide LSA which should work well in a mild boosted application.
thanx damon,, i assume i do have the peanut cam. but i have raced speed densidy cars (91/92) lb9's and have pulled on them.. and they have the hotter cam. idk, i wish i knew how to tell what cam is in there..
You can tell what cam is in there. You need a dial indicator and either a solid checker lifter, or to remove the intake and put the dial indicator directly on the edge of the lifter body, and factor in rocker ratio. Short of doing that, assume its the horrible 0.350" lift cam, which it 99.99999% is, and swap it.
Anything is better tan the 0.350" peanut cam. That thing barely opens the valves at all. I just sold a brand new custom grind 87+ roller camshaft that was specifically ground for boosted use. It was 0.495"/0.535", 222/236@0.05, and 114 LSA. So what it looks like is wide LSA is a good thing when you are building boost (otherwise, if you have lots of overlap, you are just wasting boost past the valves).
I would just buy an off the shelf cam tailored for boost, or get a custom grind. But if you are building on the cheap, the LT1 cam looks like a good choice.
The LT1 cam is real wide- like 115-116* LSA. Remember it was used in production line motors where they had to deal with fuel economy and emissions issues (overlap is a killer for both). Many stock cams are ground on much wider LSAs than aftermarket "performance" cams.
i have been reserching cams all day (my head is pounding), so far the comp 2030,2031,2032 look good,, but they have same same specs as the lt1.. in some instances the lt1 has more lift than these crane cams??,,so now im assuming performance wise, there pretty equal. with the exception of the lsa.. which would perform better? how different the sound?
The tighter the LSA the move overlap there is and the "choppier" the idle gets. Not to say it's anything you'd likely notice at idle when you're talking about cams with only 200-205* .050 duration. A couple degrees difference in the specs one way or the other doesn't make a big difference in the real world. Factory roller cams like the LT1 are still very mild. Aftermarket cams with similar specs will probably perform a bit better, but at what additional cost? You can buy good used LT1 cams off the internet for peanuts.
Even a stock LT1 cam has more than 20 DEGREES MORE DURATION than you peanut cam and a bunch more lift. It's still not all that big a cam, it's just that your current cam is SO SMALL almost anything is a fire-breather compared to it.
thanx damon. im now looking into the different varities of lt1/lt4 cams,, some years are way diff,, the lt4 looks pretty attractive(not the hot one).. i guess my last question is with 114-116lsa, boost should be great. i plan on boosting to the max 11,12+ now should i go 1.6's or 1.5's.. i read somwere while searching those cams with 1.6's could be too much for the heads?
If you're talking stock heads, the retainers will hit the guide seals around .470" lift without machining to open things up. That means a stock LT1/LT4 cam with 1.5 rockers would be near the limit of what you can shove in there as-is.
And I'm talking about the F-body version of the LT1 cam, not the smaller one used in the B-Body (Caprice). It's convenient becuase it's designed to work with 1.5 rockers, which you already have, and the lift is around .450". Here's a link to that version of the LT1 cam I'm talking about:
And, by the way, don't think this means you don't need better springs. I HIGHLY recommend you upgrade your stock springs, even with a stock LT1 or LT4 cam. Doesn't require anything exotic- a set of Comp 981 springs are a significant upgrade over stock, drop in replacement using your existing hardware, no machine work required, and work well with mild stock hydraulic rollers. I've done this upgrade on several motors with stock roller cams and it works well. Can't believe how much easier the motor revs over 5000 with half decent springs in it.
These springs alone won't allow any more lift (becuase the springs are not the limiting factor for lift in a stock head), but they do a much better job controlling the valvetrain in the upper RPMs.
now im between the 96 lt1 or lt4 production cam.. and more importantly were to find one,, ive looked everywhere, e-bay, our sponsors. cant find stock camshafts?
You should be able to find a stock LT1 cam just about anywhere. The 4th gen guys yank them and shove in something bigger all the time.
The link I posted is to the LT1 cam sold through Scoggin Dickey. You can definitely buy it from them, but at $235 for the stick I think I'd keep looking around for a good condition used one before I dropped that kind of coin.
If you're going to drop full new/list price for an LT1 cam then you might as well buy something aftermarket. That's the whole point of using the production LT1 cam- cheap and readily available on the used market.
Ask around some of the guys on this board in the TPI and TBI sections. It's a common upgrade for them.
ok, here's what i decided, im going to go with a crane copmucam either 2030.2031. or 2032. reason being i spoke to a local guy that builds tpi corvettes (also a thirdgen iroc freak) and he said on a 305 112 lsa, will be good 4 boost, and give me great all around performance, and a great sound. now i need to narrow it down to one.. thanx 4 ur help
I am not a cam pro, but I have been looking at cams for my stock 1986 305ci TPI engine running 9 PSI of boost. I have been thinking about getting the Elgin 204/214* @.050, 112 LSA with the spring/lifter kit from competitionproducts.com. It looks a lot like the compcams 2030 but is cheaper.
This is an area that i'm having a lot of difficulty myself. Cam selection... I have the 87 TPI LB9 stock cam (404/415 lift 202/207 duration) and i'm looking to change to a better performing cam. The engine is on my stand, so now it's a great time to do it! I've done a DIY porting and polish workover on the heads (I don't recall the head casting # off hand, but research indicated they were the better of the bunch). I also plan to boost the engine with a intercooled procharger. I spoke with techs at Comp Cams and they've recommended a 480/488 206/212 @50 w/ 112 LSA and a 449/456 212/218 w/ 112 LSA. Now, i thought those two grinds were quite different. I was told to stick with a 112 LSA to maintain the necessary vacume level. My concern is that I don't want to change the dynamics of the engine's power producing operating range. I don't want to move the torque and hp curve much higher in the rpm range, and loose down low. These engines are designed to produce their best below 5000 rpm, especially the torque and i want to keep it within the reasonable rpm range. I don't want to have to see 5000rpm before things get rolling. What characteristic/s of the cam would change where the max torque and hp would be developed? I also want to avoid needing any machining of heads due to lift issues. I want to increase the torque and hp numbers where the stock cam produces it's torque and hp maximums, i don't want to have to hit 6000 to find out that's where i'm gaining the hp and loosing it down low.
I don't want to end up with: (these are hypothetical figures)
So maybe this is cams 101, and i haven't found the right material to really get my hands around this , but it makes me uncomfortable not being confident with my cam selection.
Is 480in/488 lift 206/212 duration @50 too aggressive? I'm looking to get the most out of the little mouse while staying under 5000rpm. Any articles that show hp/tq results best on a cam change? (GMHT?) (CHP?)
You don't make power by NOT revving at all. Under 5k for peak power is really low. No, the 480 cam will not peak below 5k rpms. It has very short duration, so it is waaaaay more mild than the classic old school chevy 480/480 230 @0.05 cam, but still, that will probably peak around 5500 I'd think. Why are you afraid to rev? I understand not wanting to make peak hp at 7k and have zero low end torque, but when you are winding the motor up, you are getting it up in the revs anyway. As long as you have enough torque off the line, then you want to rev. At some point you start making too much low end torque w/ a torque monster motor, and you blow the tires away and waste it, instead of moving the power up in the band where it is more useable.
Stock TPI, tbi, etc third gen V8s make all their power below 5000 rpms but are also pretty slow stock.
I don't mind if peak hp is obtained 500 to 800 more than stock, but under normal driving conditions, which is where i'll be 95% of the time, i don't want to loose out on the lower end grunt. The whole design of the TPI system was designed to perform under 5000 rpm. If a cam choice develops it's best performance beyond the limit of the TPI system, it makes no sense. What ya think?
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I know there are options such as porting the plenum, bigger runners and base, BUT the dynamics are not going to change light years, and it is still a 305.
Last edited by 1987CamaroZ28; 11-29-2007 at 03:28 PM.
I think I got rid of TPI for a stealth ram for a good reason. I did not keep the TPI for the same reasons you are outlining, very restricted potential for higher rpm power. LOL I lost no noticeable low end grunt at all going TPI to stealth ram. The car still will blow the tires away but now it has like 1500 more rpm available up top where I need it. But that's a different can of worms.
Since you are keeping the long runner intake, and you have a 305, I would use the smaller of the two cams they recommended. 449/456 212/218 w/ 112 LSA. It is a 305 w/ stock heads, you do not want to go crazy overcamming it.
Last edited by 327_TPI_77_Maro; 11-29-2007 at 03:31 PM.
Thanks very much for the quick feedback. Yeah, i would like to stick with the near stock components. I'm going w/ the AS&M runners, AFPR, and have ported the plennum, did a port and polish on the heads, will be port matching the intake base, have TES headers, flowmaster, etc. No tuning on the PROM.
No prom tuning is a very bad move. I was afraid of prom tuning until I got into it. Doesn't cost much and you can control everything. You really need to be tuning when you start modding, unless you don't mind losing driveability and hp. MAF is forgiving and will still run fine w/ bolt on mods, but you will be leaving a lot on the table. The Prom tuning is every bit as important, if not more important, than any of the bolt on mod's.
You don't make power by NOT revving at all. Under 5k for peak power is really low.
Stock TPI, tbi, etc third gen V8s make all their power below 5000 rpms but are also pretty slow stock.
That is true for NA. Not true for boost. He plans on running boost. Boost changes the power curve.
You have to tune the PROM for boost. You will likely destroy the engine without PROM tuning under boost. You need to learn how to tune before running boost. As for the cam, if you like the stock RPM then run a small cam like the 206* I duration you posted.
