Any recommendations for performance mods?
Thread Starter
Instructor
Joined: Jul 2012
Posts: 185
Likes: 0
From: PA
Any recommendations for performance mods?
I was looking at these valve covers(pic below), but it seems they left out the 2 center bolt holes, I'm wondering if they have leakage issues.
All stock L98 at the moment.
So I'm tossing around the idea of new heads, what heads would you upgrade to? $350 for valve covers seems steep, so I figure why not just spend more on new heads, maybe something with an outer bolt design, and that would compliment my desired performance mods well.
Ultimately my goals for performance are in the 1500-6500 RPM range, and I have:
intake picked out(Edelbrock Pro-Flo XT, fuel rails, and TB),
still looking around for a cam(not worried about passing smog, although mine does, im not in a county requiring it),
still looking possibly for heads,
still looking for headers(only after I decide on heads, for compatibility reasons).
Links are appreciated, I am a visual type of person!
All stock L98 at the moment.
So I'm tossing around the idea of new heads, what heads would you upgrade to? $350 for valve covers seems steep, so I figure why not just spend more on new heads, maybe something with an outer bolt design, and that would compliment my desired performance mods well.
Ultimately my goals for performance are in the 1500-6500 RPM range, and I have:
intake picked out(Edelbrock Pro-Flo XT, fuel rails, and TB),
still looking around for a cam(not worried about passing smog, although mine does, im not in a county requiring it),
still looking possibly for heads,
still looking for headers(only after I decide on heads, for compatibility reasons).
Links are appreciated, I am a visual type of person!
Last edited by John.87; Oct 5, 2012 at 02:41 AM.
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
The TPI responds very well to headers, cut your air filter lid for more airflow convert to cold air intake and fit an adjustable fuel pressure regulator. Set your fuel pressure to around 45 psi, you will be around a second quicker over a 1/4 mile to low 13 sec quarters.
Heads and hot camshaft profile are not needed until you go to a mini ram setup. Keep the TPI a torque monster if you want to drive it on the streets to keep it reliable.
Heads and hot camshaft profile are not needed until you go to a mini ram setup. Keep the TPI a torque monster if you want to drive it on the streets to keep it reliable.
Race Director
Joined: Feb 2003
Posts: 11,672
Likes: 20
From: Lake Wylie SC
Good looking valve cover. Nice old school look. Only two bolt holes? Let us know how they work out. Ask the GM guys, or whomever you might buy them from, if they have leak issues and also if they have drip tangs inside.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 185
Likes: 0
From: PA
The TPI responds very well to headers, cut your air filter lid for more airflow convert to cold air intake and fit an adjustable fuel pressure regulator. Set your fuel pressure to around 45 psi, you will be around a second quicker over a 1/4 mile to low 13 sec quarters.
Heads and hot camshaft profile are not needed until you go to a mini ram setup. Keep the TPI a torque monster if you want to drive it on the streets to keep it reliable.
Heads and hot camshaft profile are not needed until you go to a mini ram setup. Keep the TPI a torque monster if you want to drive it on the streets to keep it reliable.
I actually have a Cam picked out, nothing radical. I am trying to get more past 4300 rpm when the power just dies off. I'm researching my options now because if this winter ends up sucking and I have to put the Vette away for a few months, I may use it as an excuse for a project.(Last winter I restored my CJ7)
Racer
Joined: Sep 2011
Posts: 445
Likes: 11
From: Indiana
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
John,
A stock L-98 isn't an engine designed or built to support what you want to do. It may do it for a short time, but then you'll grenade it. Remember, you're using an engine with cast crank and rods, a tiny cam, an intake manifold designed for a 305 to make torque similar to a 350 and headers that are there for looks/advertising more than performance.
If you want to reliably make power in the range you're describing, yank the engine and do a proper rebuild with a good crank, forged rods, and oiling system mods to support the RPM range you want. Alternatively, build it up as a 383, use a Super Ram or other high-flow longer tube runner setup and enjoy something that puts around 450 ft/lbs of torque to the rear wheels. There really isn't a need to rev the snot out of it to go fast.
Also, remember that stress forces go up as a square with RPM. The higher you rev it, the more stress there is. You should also replace the screw-in studs with 7/16's studs. And higher RPM means stiffer valve springs too - but the stock rollers don't deal well with that so you'll need to replace them with better rollers. It gets really expensive if you want the engine to live.
Honestly, you're a lot better off going with a 383. You can keep it mild, make a ton of torque (which is what accelerates you anyways) and not blow all the money on the high RPM parts. Let it breathe well and you'll have a very quick car for a reasonable price.
A stock L-98 isn't an engine designed or built to support what you want to do. It may do it for a short time, but then you'll grenade it. Remember, you're using an engine with cast crank and rods, a tiny cam, an intake manifold designed for a 305 to make torque similar to a 350 and headers that are there for looks/advertising more than performance.
If you want to reliably make power in the range you're describing, yank the engine and do a proper rebuild with a good crank, forged rods, and oiling system mods to support the RPM range you want. Alternatively, build it up as a 383, use a Super Ram or other high-flow longer tube runner setup and enjoy something that puts around 450 ft/lbs of torque to the rear wheels. There really isn't a need to rev the snot out of it to go fast.
Also, remember that stress forces go up as a square with RPM. The higher you rev it, the more stress there is. You should also replace the screw-in studs with 7/16's studs. And higher RPM means stiffer valve springs too - but the stock rollers don't deal well with that so you'll need to replace them with better rollers. It gets really expensive if you want the engine to live.
Honestly, you're a lot better off going with a 383. You can keep it mild, make a ton of torque (which is what accelerates you anyways) and not blow all the money on the high RPM parts. Let it breathe well and you'll have a very quick car for a reasonable price.
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Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
How much power,how much money and how fast do you want the car to go? What year L98 is this and is it a stick or auto?
With a 6500 redline goal you want to start shopping for a new intake manifold(Ie Super ram,Mini ram) if staying fuel injected and a camshaft....
With a 6500 redline goal you want to start shopping for a new intake manifold(Ie Super ram,Mini ram) if staying fuel injected and a camshaft....
Thread Starter
Instructor
Joined: Jul 2012
Posts: 185
Likes: 0
From: PA
John,
A stock L-98 isn't an engine designed or built to support what you want to do. It may do it for a short time, but then you'll grenade it. Remember, you're using an engine with cast crank and rods, a tiny cam, an intake manifold designed for a 305 to make torque similar to a 350 and headers that are there for looks/advertising more than performance.
If you want to reliably make power in the range you're describing, yank the engine and do a proper rebuild with a good crank, forged rods, and oiling system mods to support the RPM range you want. Alternatively, build it up as a 383, use a Super Ram or other high-flow longer tube runner setup and enjoy something that puts around 450 ft/lbs of torque to the rear wheels. There really isn't a need to rev the snot out of it to go fast.
Also, remember that stress forces go up as a square with RPM. The higher you rev it, the more stress there is. You should also replace the screw-in studs with 7/16's studs. And higher RPM means stiffer valve springs too - but the stock rollers don't deal well with that so you'll need to replace them with better rollers. It gets really expensive if you want the engine to live.
Honestly, you're a lot better off going with a 383. You can keep it mild, make a ton of torque (which is what accelerates you anyways) and not blow all the money on the high RPM parts. Let it breathe well and you'll have a very quick car for a reasonable price.
A stock L-98 isn't an engine designed or built to support what you want to do. It may do it for a short time, but then you'll grenade it. Remember, you're using an engine with cast crank and rods, a tiny cam, an intake manifold designed for a 305 to make torque similar to a 350 and headers that are there for looks/advertising more than performance.
If you want to reliably make power in the range you're describing, yank the engine and do a proper rebuild with a good crank, forged rods, and oiling system mods to support the RPM range you want. Alternatively, build it up as a 383, use a Super Ram or other high-flow longer tube runner setup and enjoy something that puts around 450 ft/lbs of torque to the rear wheels. There really isn't a need to rev the snot out of it to go fast.
Also, remember that stress forces go up as a square with RPM. The higher you rev it, the more stress there is. You should also replace the screw-in studs with 7/16's studs. And higher RPM means stiffer valve springs too - but the stock rollers don't deal well with that so you'll need to replace them with better rollers. It gets really expensive if you want the engine to live.
Honestly, you're a lot better off going with a 383. You can keep it mild, make a ton of torque (which is what accelerates you anyways) and not blow all the money on the high RPM parts. Let it breathe well and you'll have a very quick car for a reasonable price.
Looks like I would be better off buying a block and building it and just set the L98 aside. Seems like as great as our C4's are, GM really dropped the ball on building the engines properly. BTW my Vette is an auto, and I'm aware of the shortcomings of the D36 rear.
The cam I'm looking at is a Hydraulic Flat Tappet Cam and lifters with power in the 1500-6500 rpm range. Same with the intake. I have a set of long tubes picked out, but that may change. As far as heads, I'm looking at some Aluminum Dart heads, still unsure with those though.
Power - something respectable, 275-300 ish
88 auto.
Last edited by John.87; Oct 6, 2012 at 06:06 PM.
Burning Brakes
Joined: Jan 2000
Posts: 831
Likes: 31
From: Merritt Island Florida
Okay with that much power wanted you will need to ditch the TPI and go with a shortrunner intake manifold(ie Superram,Holley or Mini ram) especially with the cam you chose. The cam with a long runner intake will result in a car that has no low end power and will not rev. Your trans will not like 6500 rpm shifts either so that needs to be upgraded as well as an ignition upgrade.
The drawback is that these type of intakes are expensive.
Now if you don't mind the car making power to 5000-5200 max then you can keep the TPI but you will need to get a cam that matches it in terms of duration(your powerband).
Till you sell your Ford stuff go with the minor stuff that works. Advance your ignition timing,tune up the car(wires,plugs,fuel filter) and insure the motor is healthy for mods(compression test,leak down test-go to Youtube and look up vids that show you how to do this). Clip your front airbox,run long tube headers(TPIS ones are nice),high flow car and a good cat back for starters. Port your upper plenum and look out for nice runners used since you are on a budget(SLP are nice and can be ported,Arizona and Marine/TPIS runners are the same but I think they are discontinued new). A nice base lower intake manifold like a big mouth from TPIS is not bad either. I have had good luck with pulley kits on L98s. Some Vette guys don't like them.
Once you do those mods and do a converter and upgrade the transmission for future mods since its out. Then get back to us for more advice
Read up here as well
http://temp.corvetteforum.net/c4/vader86/
The drawback is that these type of intakes are expensive.
Now if you don't mind the car making power to 5000-5200 max then you can keep the TPI but you will need to get a cam that matches it in terms of duration(your powerband).
Till you sell your Ford stuff go with the minor stuff that works. Advance your ignition timing,tune up the car(wires,plugs,fuel filter) and insure the motor is healthy for mods(compression test,leak down test-go to Youtube and look up vids that show you how to do this). Clip your front airbox,run long tube headers(TPIS ones are nice),high flow car and a good cat back for starters. Port your upper plenum and look out for nice runners used since you are on a budget(SLP are nice and can be ported,Arizona and Marine/TPIS runners are the same but I think they are discontinued new). A nice base lower intake manifold like a big mouth from TPIS is not bad either. I have had good luck with pulley kits on L98s. Some Vette guys don't like them.
Once you do those mods and do a converter and upgrade the transmission for future mods since its out. Then get back to us for more advice
Read up here as well
http://temp.corvetteforum.net/c4/vader86/