Dan87IROC-Z

Why do you all say the LT4 HOT cam won't work for the L98? It sounds like the ideal cam, it only costs $190. Its a good price, I wouldn't want to spend $375 for the ZZ9 cam when I could get a better cam for $190. The ZZ3/ZZ4 is too small, the LPE cams are only single pattern, that leaves the ZZ9 and the LT4 HOT cam, the LT4 is better and cheaper, so whats the deal????

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Steve91Z28 L98

I could be wrong but isn't the LT4 Hot Cam a single pattern also?

And if you're asking if this cam is good for a basically stock L98 like yours then the answer is no. Especially since you have those 2.77 gears. This cam is good for higher rpm motors. The stock tuned port is not suited for high rpm. You would at leats need some large tube runners(preferably siamiesed) and a high flow base. Even then, you probably wouldn't get the full benefit from it. A Superram or Miniram would be the way to go.

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1991 Z28 - 350 TPI, T56, Centerforce Dual Friction clutch, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, no cats, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Steve Spohn adjustable torque arm and T56 crossmember

Yelofvr

The specs for the LT4 Hot are:
218/228dur @ 050 .525/0.525lift 112 lobe sep. So it is a dual pattern. Steve, I think your recomendation is right on the money. If you read Lingenfelter's book about cam selection, the use of a 218 intake duration cam would need more air than a stock TPI could flow. Both he and SLP have done alot of TPI motors, trust what they recommend!

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Dave Zelinka

Kevin91Z

iTrader: (1)

Why is the ZZ4 cam too small? I think its great for my engine. 285 HP, 380 TQ at the rear wheels. Stock, ported TPI intake.

The LT4 hot cam is a pretty big cam. Its range is 2500-6500. Stock TPI dies off at 4500. So just when the cam is starting to make its power, you choke it off with low-flow intake and heads. Thats why people say its not the best cam for stock TPI.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

Dan87IROC-Z

Well, if you look at all the things I can do now, the best bang for the buck has to be the cam. I am not going to spend $400 on an intake, when its only going to give me 10HP. You know what I mean, and next summer when I get my AFR heads I don't want a cam that is going to be under performing. The LT4 cam is not too big to the point where it will hurt my car, I know that. It has to make somthing of a difference.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Kyle F

what they are all saying is the Intake on the TPI and runners and ignition system is not made to run over 4500 RPM. Yes the intake will only give you 10 hp, but say after you install the cam and heads and the engine needs to breathe over 4500 rpm that intake(lke a mini ram) may yield 30 - 40 hp even. Just your set up right now is not needing a LT4 HOT cam, but with the heads and a new intake plus a set of 3.73 gears you will be able yo use it. Matching everything up is the way to go, also take into consideration what you are building toward. I mean I have 305 heads on my 350 right now because I buit it with Low compression pistons for NOS so Instead of buying a cheaper set of heads now i decided to use my old ones to keep compression up and make HP now until I can afffor a set of AFR heads that match my cam and copression I want to run so I can safely run a 150HP shot or supercharger. Ofcourse I still have gears and a custom prob to go to after I get my heads and do a couple of other mods. Hey the most important thing is to consider where you want to be when you are finsihed and build to it. Yes you engine will run with the LT4 HOT cam, but you will be able to release a lot more out of you engine later with gears, ingnition, heads, and yes you will eventually need an new intake or port yours.

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86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank, bearings, rings, and magnafluxed rods. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,SVO 24# injectors,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace
http://geocities.com/SunsetStrip/Garage/9548/kyle.html

Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

firebird87

You guys are totally missing the point of why a zz4 or a zz9 cam will not work well for your L98 motor Yes you are partial right about the duration being to a little big (zz9 cam) with the 2.77 gears but the point everyone is missing is the intake centerline of this two cams which have a 4 degree advance grounded into them. Due to the long runner design, TPI engines like cams with about 114-lobe separation and about a 110-centerline (which is straight up no advance) the other two cams were design for the short runners like Lt1 and the miniram.
Take a look at any cam company who make cams for the tpi motor and will see most tpi cams have no advance grounded into them. If you decide to use the zz9 cam you would need to retard the cam to achieve close to the 110 centerline I was talking about. GO to the comp cam sight and look at their tech articles, which explains what I am talking about in detail. I have online a very detail article about this subject from GM High Tech which explains the principles for cams for tpi engines. Please let me know if any wants a copy.

Thanks

theformula

Firebird87 is correct. Remember, the ZZ9 was not meant for TPI or LT1. TPIS stated it was made for a carbaurated engine. That's from them directly.

Kevin91Z

iTrader: (1)

Ok, I call BS. One, installing a cam straight up is 108º centerline. 110º is two degrees retarded.

Two, TPIS doesnt offere any carb products. They specialize in L98/LT1/LS1. The ZZ9 cam was made specifically for the L98 Corvette engine, modeled after the ZZ4 cam. It says this in their Insider Hints book, and also on their webpage here: http://www.tpis.com/pg13-16.html

BadSS

OK folks. If you have a cam ground with a 112 degree lobe spread / separation - "straight up" indicates that the intake centerline is installed at 112 degrees as well as the exhaust centerline at 112 degrees. However, most cam companies "add" 4 degrees advancement so that when you install the cam "straight up" via the timing chain indicator (zero advance at the chain/gear drive/belt),, the intake center will be 108,, and the exhaust center will be 116. Technically a 112-degree lobe separation with a 110-intake center is 2 degrees advanced.

As far as cams I can only speak to my personal experience with one TPI hot rod. I'm running a 218/228 with a 110 spread advanced 2 degrees (108-intake center),,, and the thing is a beast!!!! see sig. I'm having idle richness problems but hope to work that out with a chip. However,,, I know this cam's shift point was 5700 with a carb with these heads and a Victor,, and while it will pull to 5700 with the TPI,,, it will run a better time short shifting at 5300 to take advantage of the tremendous torque this TPI has. So long story short,,, I by no means consider myself a TPI expert (yet),, but if I were doing it over,,, I'd go with something around a 212/224 on a 112 or 113 spread,, however I will not pull this cam out to put another in!!!!


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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 1 5/8" Headman headers, 3" Dyno-max, TH350, B&M Megashifter, 3.23 peg leg, 245/45ZR17s on 212 Eagles

Dan87IROC-Z

I know the intake needs to be freed up with to get the full potential with a new cam, I also know you need to match it with gears, higher stall speed and heads. I know all that I am quite knowledgeable when it comes to TPI motors. I don't have $1200+ to spend on new heads or a miniram now, although those mods are down the road. I have searched and searched for a 9 bolt rear end with a set of 3.45s and it is impossible to find. I also don't have the money now to buy a new 3.70 ring and pinion set along with the carrier and all the other stuff and the cost to have it installed.
My main question was, with heads, intake, gears and stall all comming down the road, is the LT4 HOT cam really that bad of a choice? I know it HAS to make my car faster, its not like I am putting a ZZ-X cam in my car or anything. Plus the price of the LT4 Cam is ideal, $190. I will probably be purchasing a set of AFR 190s or 195s this comming summer. The way I looked at things, the cam seems like the best choice now, does any one STRONGLY dissagree with that? I mean, for under $300, what would get me more, nothing I can think of.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Scott 88 GTA

Dan, I would say go ahead and get it. I just put a new motor in my car, since my old one spun a bearing. When I bought my new one I decided to upgrade the heads and cam, since I figured it would be easiest now. I chose to go with the LT4 HOT cam because it is so inexpensive, as you mentioned. However, I still have the stock TPI sitting on top of my engine since I couldn't afford to upgrade it too. Now since I only have just over 100 miles on my new engine I can't tell how it performs above 4k rpm, but below it it pulls hard! I've made a few half-throttle runs from about 2500 rpm up to 4000, and it's building power all the way up, even with the "restrictive" stock TPI on top of it. The stock engine peaked at about 3700 rpm or so. So either way, this combo has definately moved the rpm range of the engine a substantial bit higher. I don't think the HOT cam is as much of a mis-match with the TPI as most people think. Tom Keliher is running it with good results in his Formula too. I say go fot it, or if you want to, wait a few more weeks until I hit 500 miles and can give you a better description of how everything works on my car.

Later

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Black 88 GTA L98
New engine is in!
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back
E.T.F.A Member #11

Dan87IROC-Z

Finally, I get someone with personal experience, not just people speculating. I have a friend with a TBI 305 and only a cat-back and his SLP cam made like a 1/4 differnce of like at least .5 seconds. Thanks, too all of you for responding!!!!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Dan87IROC-Z

Finally, I get someone with personal experience, not just people speculating. I have a friend with a TBI 305 and only a cat-back and his SLP cam made like a 1/4 differnce of like at least .5 seconds. Thanks, too all of you for responding!!!!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

F22Raptor

You call that a big cam? Give me a break!
I have an Extreme Energy CompCam that specs out to:
230/236* Duration (I/E)
510/520" at .050 Lift
110 Lobe separation Angle
Installed straight up!

This is obviously WAY bigger than the not so hot "HOT" cam except for lift (slighty less).
I have to admitt that the idle quality is not great (thanks to my 110 Lobe Angle) and it does gets on my nervers sometimes, but you also have to consider that I still have the crappy Hypertech chip and also have a little dilemma with my ignition which is amplifying the roughness big time.
Now the good news, The car pulls like a train and will sometimes break traction at 30-40 MPH with 3.54s in the rear and huge 275 50 16 tires (no, it doesn't smoke the tires, but the rear does come loose). There was a big torque increase and horsepower increase when I put this baby in and also lower my et's by more than 4 tenths, which is totally opposite to what 99.5% of the people in this board would think. I do have to tell you that I have an Edelbrock base, ported SLP runners, ported plenum and 58 mm TB-(which definately killed my torque a bit), but the "HOT" cam is much smaller and besides, if you want to modify the engine, you have to start somewhere and I think the cam is a good place. Once you find the money, improve the intake and so on. One more thing before I forget, I really hope you have headers, because you will need them more than intake stuff. In fact, that should be the first real mod after all the free mods are done. I guaratee you it will lower your et's by about 3 tenths or more on a 350 engine.
Just my 2 pennies!
Rick

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

Dan87IROC-Z

Ohh yes, I do have headers, they were the first mod I did to my car (after all the free BS that is) and they are by far the best. Thanks a lot, all of you.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Soon to come: LT4 HOT Cam, Air Flow Research 190cc or 195cc Heads, 2800 RPM Stall Converter and SLP 3.70 Rear End Gears.