LT1-LT4 Modifications 1993-97 Gen II Small Block V8

L98 Performance Help

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Old 05-31-2007, 09:50 AM
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383astro... I'd be interested in the stroker kit if it was for a one piece seal. Please forgive my hesitation on the TPI... I'm still looking for and weighing my options.

Formula350... Is this the Ramjet EFI kit you mentioned? Where did you find it for $1300? http://store.summitracing.com/partde...5&autoview=sku
Old 05-31-2007, 10:02 AM
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you want cheap, dependable HP?

i dont know why nobody has suggested this, but, sell your heads. freshen up the bottom end and get a good set of vortec heads from GMPP. match that with a good intake within the range a the cam you choose. use a good hydrualic roller around 220* @.050 or so. top it all off with any carb of your choice. thats about the easiest, cheapest 400hp out there today. i believe CarCraft did a little Vortec headed build a few months back. i'd have to look again. either way, you can do this for around $1200, if you dont need alot a machine work and dont have to replace things like your crank or rods. not to mention, whatever money you get for the heads. just a thought.
Old 05-31-2007, 10:07 AM
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you can buy a seal adapter for like 25.00. I understand on the TPI. Weigh your options and let me know. I dont have but a couple of people interested in the 383 kit.

The vortec head option is also a good way to go. Those heads I think can make more torque than the L98.
Old 05-31-2007, 10:16 AM
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or you could do the lt1 head and intake conversion.
250.00 lt1 heads
100.00 intake w/tb and injectors
200.00 having intake adapted for reg distributor
100.00 having heads adapted for gen1 block
0.00 cam from me makes you a stock lt1 with 275HP

650.00+/- makes you an LT1 pretty much and you can usually get 300-400 for the L98 aluminums.

or...

do the above but sell the L98s and get the heads ported then throw in a cc306 or gm847 for 250.00, 918 springs for 150.00, pushrods for 90.00, etc.
Old 05-31-2007, 10:33 AM
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LSXNV... I don't think the bottom-end needs anything... only 32K miles on it (so I'm told). It does look very clean.

ALL... Will "any" Gen1 heads/intake fit the L98? If so, maybe I'll swap some parts from the ol' SBC and just buy a new cam. Heads are port-matched Edlebrock Performer RPM and a dual quad Edelbrock RPM Air Gap intake/carbs. Do the heads require special springs for a roller cam? Will the shorty block-hugger headers swap over?
Old 05-31-2007, 10:46 AM
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you can put any old school intake on the vette L98 heads,the cast iron L98s require the two center bolts on each side to be modded.
i would always replace springs to a stiffer aftermarket spring,most cars pick up a few tenths just by doing this....either the bee-hive spring or have the head machined buy the spring seats for alum.heads and put the 987 comp spring in there you will be happy in the end.
as far as the headers i do not really care for the regular block huggers however SANDERSON makes a set that work really well.
Old 05-31-2007, 10:46 AM
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ALL... Early in this thread I became open-minded regarding TPI vs EFI vs carbs. Until very recently I was dead-set on using the latter. Can anyone with experience installing/tuning/running 2 or all 3 give me a list of pros/cons? NOT regarding performance... just installing/tuning/running.

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Old 05-31-2007, 10:56 AM
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96lt1m6... Can I put my Gen1 non-L98 heads on my L98 block?

Regarding headers... I have very limited choice if I use the Jags That Run brand of engine swap kit. It sets the block back against the firewall and there are clearance issues with steering and other parts when other headers are used. I could keep the Hooker brand swap mounts but this moves the engine about 4 inches forward, which necessitates the use of pusher style electric fans when used with an electric water pump... but this kit allows use of long-tube headers. MSA makes a swap kit that places the engine about in the middle of the other two. I can't remember the brand but there is a set of semi-long-tube headers that work with the latter kit. I'm rambling... sorry.

BTW, I do NOT need to worry about passing emissions. The car is a 1974 and I'm in Texas

Last edited by Mike1234; 05-31-2007 at 11:05 AM.
Old 05-31-2007, 11:31 AM
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interesting build...and interesting looking Z. didn't have the cash for one of the original 32 series 1 '62 Ferrari 250 GTO??? i understand...they sell at auction for a few million$. put some wire wheels on your's and at a glance it could have the look. Looks like you're building a quick little car!!!
Old 05-31-2007, 11:33 AM
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i am rusty on my smal block chevy stuff, but as long as you are not running the TPI intake, you can swap any earlier head on an L98. another alternative for a little more money is GMs Fast Burn heads. if you go carbed, you wont need a computer. you wont even need a coil or box if you decide to go with HEI ignition. just fuel it and go. the money you save not having to rebuild the long block can be used on purpose built swap headers. but, if you have the engine out, it is good insurance to freshen up the bottom end.
Old 05-31-2007, 11:40 AM
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Originally Posted by Formula350
I should've guessed, LT1 people talk **** about TPI, just like the LS1 and LT1.

Grow up, will ya? There is plenty you can do to the TPI setup that lets it rev higher and keep making power. Unless you're going to give him a great deal on a L98 ready LT1 intake with the distributor boss, then leave him be. I've ran TPI and LT1 and I love them both.
Lt1 people talk ****? I wasn't talking **** at all. I was providing the truth. You should also take note what my last car was. It was a 1991 WS6 Trans Am L98 auto in Gunmetal Grey. So I know a few things about the TPI setup. To be completely truthful, I haven't even driven an LT1 car yet as I bought mine without a drivetrain and I'm just now putting it back together.

Mike, I asked how much you had, because GM offers the Ramjet kit for $1,300 and all you need then is the ECM and Harness. I don't know if you can use a TPI ECM and Harness, but if not thats another $700~ (500 ecm and 200 harness). The Ramjet is basically like the Holley and TPiS Rams, but uses a bit different TBody. Looks like a cross between an LT1 and TPiS Miniram. It comes with EVERYTHING you need too, intake, injectors, TB, air filter, rails etc etc etc.
Honestly I wouldnt waste my time or money on the RamJet. You HAVE to run the RamJet ECU and harness and it requires a special tuning device (like the GM Tech2) in order to tune it.

I'm still saying he should pick up the set of Patriot Performance heads off either the Patriot Performance website or off ebay if he can, buy a used Lt1 intake and have it converted, and then have a custom cam ground (thunderracing.com has a special deal going on with a member here for a great price on cams and I can find his name if you want) and then run a either a stock harness and ecu from a TPI thirdgen OR run a Megasquirt (I can provide more information if you want) ecu which is a very badass setup that I will be switching to on my LT1 later this year. After he gets all the prom burning crap and a laptop, that will come out near the price of the Megasquirt. The tuning software for Megasquirt is free to download and is open source so new features are constantly being added.
Old 05-31-2007, 04:09 PM
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gallardo259... Thanks for the kind words. I can't take credit for the build though. I bought it with the body kit and engine swap already done. No... I can't afford one of the originals. If I could though... I'd buy a BUNCH of fun hot rods, classics, and fakes instead. I can't imagine any one car being worth millions, LOL!! Wire wheels are a future upgrade but Dayton's Borrani replicas cost $2-2.5K for the set. It's pretty quick with the Gen1 that's in it now but it seems to run out of breath near the top-end... could be the Edelbrock 650 CFM carb... or a weak ignition system... or lack of sufficient fuel flow (the most likely culprit). I'm hoping a well-chosen roller cam with matched heads, induction, exhaust, larger fuel lines and better pump will make it really scream.

LSXNV... Okay, so I can swap the Edelbrock heads onto the L98 and relegate the ol' sbc to wearing the L98's... probably should put a low-rev torquey cam and low-rise intake on the SBC to match things up. BTW, the older motor will be transplanted into another 260Z project. I already have a Crane digital ignition, coil, and a window switch for nitrous so I might as well put it on the L98. By freshen up the bottom end... you mean just new bearings, bolts, and rings, right?

1bdbrd... The ol' gears in my brain are still grinding... I've slowed my decision-making down a bit. No more rash decisions this year... err, week... or so. Yes, I would like the name of the member with the cam deal. If I decide to go EFI, I think the Megasquirt is my best option... might as well, I guess. Besides, I don't own a laptop... or a blackberry... or even a cell phone. See... I really am a cheap old bastage.

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Old 05-31-2007, 04:45 PM
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yea, if you have everything, go for the swap. and since you don't have to spend so much on the top end you might consider beefing up the bottom end some, for the nitrous. small block chevy stuff is so cheap and easy to find. if not, have the crank magged and perhaps polished, if it doesn't need turned. recondition the rods, and re-ring and hone. i wouldn't run those pistons if you use the nitrous. cast pistons shatter like glass with a little abuse. there are a number of well priced rotating assemblies out there for your engine as well.

i like to over build the bottom end for my intended HP numbers. because nitrous is sooo easy to just bolt on and go. that, and i have been known to "over-rev" an engine in the burnout box.
Old 05-31-2007, 05:34 PM
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Well, since you can toss on any SBC carb intake, you might as well just do that. You could have your motor in and running in a weekend going that route.

http://www.gmpartsdirect.com search for 12498032. They don't have the ECM, just the harness.

I still say run a modified LT1 intake. If you can run a LT1 intake on a TPI harness and ECM, then you're golden. If you want, Painless sells the TPI harness for $300, ready to go.
Old 05-31-2007, 07:12 PM
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Originally Posted by LSXNV
yea, if you have everything, go for the swap. and since you don't have to spend so much on the top end you might consider beefing up the bottom end some, for the nitrous. small block chevy stuff is so cheap and easy to find. if not, have the crank magged and perhaps polished, if it doesn't need turned. recondition the rods, and re-ring and hone. i wouldn't run those pistons if you use the nitrous. cast pistons shatter like glass with a little abuse. there are a number of well priced rotating assemblies out there for your engine as well.

i like to over build the bottom end for my intended HP numbers. because nitrous is sooo easy to just bolt on and go. that, and i have been known to "over-rev" an engine in the burnout box.
Ahh...you guys are killin' me. I know this is all good advice though!! But ya know... if I'm gonna go to that much trouble and expense I'm sure as heck gonna stroke the thing I don't want to just kill Mustangs... wanna PULVERIZE 'em!!!!
Old 05-31-2007, 07:18 PM
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Originally Posted by Formula350
Well, since you can toss on any SBC carb intake, you might as well just do that. You could have your motor in and running in a weekend going that route.

http://www.gmpartsdirect.com search for 12498032. They don't have the ECM, just the harness.

I still say run a modified LT1 intake. If you can run a LT1 intake on a TPI harness and ECM, then you're golden. If you want, Painless sells the TPI harness for $300, ready to go.
I may do just that... I'm still researching and thinking. Please give me your arguments for LT1 vs carb. I believe I now understand the difference between TPI (lots of low-end torque but runs out of breath above 5300) and LT1 (less low-end torque but breaths better up top)... sort of like the difference between Gen1 carbed low-rise dual plane manifolds and slightly higher-rise single plane, yes???
Old 05-31-2007, 08:26 PM
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Your carb intake compare is pretty close, yea. Since your Z is setup for a SBC, why not just toss that one in there, and have it all ready to go with the carb intake on it. Then when you figure out what you want to do (assuming you don't stroke it), all you'd have to do is either pull the intake off, or pull the intake and heads off.

Personally, if I had the $$, I'd get a LT1 intake and heads machined for the GenI block and then run that. If you want to run a carb intake, I'd run something like this
www.gmpartsdirect.com
Part# 10051102

I'm sure Edel or Holley makes one similar for less than $300, but who knows. I suppose it's really not all that bad of a price. Run a nice Demon 650cfm It'd def look aggressive as hell!
Old 05-31-2007, 09:50 PM
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Formula350... So you like the single-plane higher-rise intakes for carbs. You're saying an LT1 is more similar to that? That's an even bigger difference than I expected (L98 TPI vs LT1).
Old 05-31-2007, 10:08 PM
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Originally Posted by Mike1234
Formula350... So you like the single-plane higher-rise intakes for carbs. You're saying an LT1 is more similar to that? That's an even bigger difference than I expected (L98 TPI vs LT1).
Well the LT1 makes only a little less Tq than the TPI but more HP and higher on the RPM band. However, that doesn't mean the TPI sucks like 1bdbrd implies. If you had a TPI readily available to you, I wouldn't turn it down. If you don't have either available to youy, why not just go with that carb I listed. I don't know it's RPM range, since it didn't list it, but I think it's 2000-6500. Even if it's 2200 you can get a stall to get there, and I'd run a 2200 on the road. It's just once you get into bigger stalls, the gas mileage goes down.

With the weight of you car, you don't need as much as you're thinking. 400hp for you is like 550hp for us. You've got 1/2 a ton less weight on us. And a mustang weights about the same as a FBody, so you don't need to worry about smoking one, even with a stock TPI or LT1 motor. Heck, I never lost to a Mustang in my TPI Firebird.
Old 06-01-2007, 11:27 AM
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Formula350... So TPI is to LT1... as Edel. Performer RPM is to Edel. Torquer. I MUCH prefer the Edel. RPM. Decision made... no TPI. I'm installing a 2500 RPM stall converter so an adapted/ported LT1 matches very well. I'm told that, in a car this light, a 2.5K-3K stall converter drives almost the same as a stock converter... may not even be able to tell the difference until I need it.

The intake you suggest looks an aweful lot like an Edel. Super Victor, which is good from 3500-8000 RPM. I'd need a 4K RPM stall converter for that, wouldn't I? I'd need one heck of a cam too. I don't think this motor will last long above 7K RPM. It would be a SCREAMER for sure but I'm looking for a combo that's good for a daily driver.

The car has a ~350 FWHP SBC in it now and it's okay... but it's far from enough. Id be very please with 700 FWHP... 500 WHP... more is even better, heh, heh. It's a matter of what I can afford.

When I started this thread I would have been happy with 400 WHP... but I'm getting greedy... mwah-ha-ha-ha-ha... [wringing hands with an evil grin].


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