Go Back   Corvette Forum > C4 Corvettes, 1984 - 1996 > C4 Tech/Performance
Sign in using an external account
Register Forgot Password?
Register Search Today's Posts Mark Forums Read FAQ Vendor Directory
Search
C4 Tech/Performance
L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine Sponsored by
J&D Corvette

Welcome to Corvetteforum.com!
Welcome to Corvetteforum.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Corvetteforum.com today!


Corvette Store
 
 
C7 Parts & Accessories
C6 Parts & Accessories
C5 Parts & Accessories
C4 Parts & Accessories
C3 Parts & Accessories
C2 Parts & Accessories
C1 Parts & Accessories
Wheels & Tires
Sponsored Ads
 
 
Vendor Directory
  
Reply
 
 
 
 
Thread Tools Search this Thread
Old 01-23-2011, 11:26 AM   #1
SkipRiggs
Junior Member
 
Member Since: Nov 2010
Default Wanted: Advice on L98 Engine Upgrades

Hi Folks, I have a 90 L98 Vette. I'll state my problem first; I am going to take my L98 in for a rebuild and before I make that big jump I would like to have some of your suggestions for improvements. Some things I thought of were timing chain and oil pump. I would like some performance mods but I don't want to alter the ECM very much. In other words, what can I do with the engine internals only. Thanks so much for your help. Skip, 90 L98 Vette, 91 ZR-1 Vette
SkipRiggs is offline   Reply With Quote
Old 01-23-2011, 11:47 AM   #2
l98tpi
CF Senior Member
NCM Sinkhole Donor
Support Corvetteforum!
 
l98tpi's Avatar
 
Member Since: Nov 2008
Location: Monroe OH
Bob Armstrong
Default

Here is one I'll give, although I don't know if this is what you're looking for. Get good high quality head gaskets or you will pull the engine back apart sooner than you want. Don't purchase the cheap AutoZone set.
l98tpi is offline   Reply With Quote
Old 01-23-2011, 11:47 AM   #3
silverdroptop
CF Senior Member
 
Member Since: Nov 2003
Location: Ringgold GA
Default

If the engine is being rebuilt why not stroke it to a 383 then install a mild cam and have the heads ported and freshened up and install matching valve springs if you want to stay with your factory heads and then you can upgrade your intake system and exhaust system either when you rinstall it or at a later date.
silverdroptop is offline   Reply With Quote
Old 01-23-2011, 01:01 PM   #4
nutz4c4
CF Senior Member
 
nutz4c4's Avatar
 
Member Since: Nov 2005
Default

Quote:
Originally Posted by Pete K View Post
Looking forward to hearing the recommendations myself. This topic does not come up often enough.
nutz4c4 is offline   Reply With Quote
Old 01-23-2011, 01:06 PM   #5
8388
CF Senior Member
St. Jude Donor '14
 
8388's Avatar
 
Member Since: Aug 2000
Default

Quote:
Originally Posted by Pete K View Post
Looking forward to hearing the recommendations myself. This topic does not come up often enough.
Here's one. Insert an LS3
8388 is offline   Reply With Quote
Old 01-23-2011, 01:16 PM   #6
8388
CF Senior Member
St. Jude Donor '14
 
8388's Avatar
 
Member Since: Aug 2000
Default

Quote:
Originally Posted by Pete K View Post
Now we are cooking with gas!
No, that's an LS9
8388 is offline   Reply With Quote
Old 01-23-2011, 01:30 PM   #7
Black89Z51
Suckin' gas, haulin' ass.
Support Corvetteforum!
 
Member Since: Apr 2010
Location: Newport News Virginia
Default

If you want to do a stock rebuild, I would go with some flat top pistons and H series clevite bearing with a decent sized cam.

If you want to modify internals, go with a 383 stroker build.
Black89Z51 is offline   Reply With Quote
Old 01-23-2011, 03:23 PM   #8
steven mack
CF Senior Member
 
steven mack's Avatar
 
Member Since: Oct 2006
Location: Stafford Connecticut
Default

A 383 is not that much more time or money these days.
steven mack is offline   Reply With Quote
Old 01-23-2011, 03:29 PM   #9
383vett
CF Senior Member
 
383vett's Avatar
 
Member Since: Apr 2003
Location: moraga ca
Default

Quote:
Originally Posted by Pete K View Post
Looking forward to hearing the recommendations myself. This topic does not come up often enough.
Pete, I thought you wrote the book.
383vett is offline   Reply With Quote
Old 01-23-2011, 03:32 PM   #10
WW7
CF Senior Member
 
WW7's Avatar
 
Member Since: Aug 2007
Default

Quote:
Originally Posted by steven mack View Post
A 383 is not that much more time or money these days.
Just alot more power!!!....WW
WW7 is offline   Reply With Quote
Old 01-23-2011, 06:01 PM   #11
John A. Marker
CF Senior Member
 
John A. Marker's Avatar
 
Member Since: Mar 2004
Location: Dublin CA
Default

..... not getting a custom chip...just go for good parts. I would have the rotating assembly balanced. This consists of the crank, pistons, rods, balancer and flywheel. Balancing is about the most you can do for the bottom end. You could go for higher compression pistons, but you are at that fine line with your chip being able to handle this or not.

To get a little more out of the engine (again not touching the chip), go for a good set of heads and upgrade to roller rockers. Take a grinder to the intake, runners, plenum and gasket match by taking out the excess material to match the gasket holes. You can do the same for the exhaust manifold. The gasket matching will not provide much in the way of HP....but it all adds up.

Want power.....get the cam and pay the $$ for the custom tune....you will be much happier.
__________________
1995 LT1 6 speed - stock.
SOLD to son ** 1985 Coup -ZZ4 balanced, LPE 74211 , AFR 180 heads, SuperRam base, runners & plenum, cut out air box, K & N , power coupler, 52MM TB, March pulleys, AFPR, Accel injectors, Walbro FP, 1.6 RR, chip by TJWONG, 160 stat, cut back plugs, 8.5MM MSD wires, custom camber-brace,TRANSGO shift kit, 2400 stall converter, cross drilled rotors, SS brake lines, VBP camber rods, IAS Edelbrock shocks, exhaust, Magnflow cat, 3.07 gears, 13.2 @107.2 MPH in 1/4

Last edited by John A. Marker; 01-23-2011 at 06:14 PM.
John A. Marker is offline   Reply With Quote
Old 01-24-2011, 11:42 AM   #12
TheCorvetteKid
CF Senior Member
 
TheCorvetteKid's Avatar
 
Member Since: May 2002
Location: The Motor City
Default

Quote:
Originally Posted by John A. Marker View Post
To get a little more out of the engine (again not touching the chip), go for a good set of heads and upgrade to roller rockers.
Changing to "a good set of heads" will absolutely require a retune (ie: a chip) in order to maximize power gains and to get the engine running at optimum. In fact, any change which significantly impacts air or fuel flow will require a retune.

To the OP:
The answer(s) to your initial question are:

1. How much are you willing (or looking) to spend?
2. What are your final objectives for the car (race-only use, road-burner, reliable daily driver, etc...)?

Generally speaking, if you're looking to just 'freshen-up' the engine on a modest budget, then upgrading some of the 'weaker' items is a great idea. Spending those extra dollars for a true double-roller timing chain, high-volume oil-pump, and (if your budget allows) a forged crankshaft will be money well spent. If the stock connecting rods are in good condition, you can have them balanced before being reinstalled; stock L98 connecting rods are a lot stronger than most people give them credit for. If I am not mistaken, 1990 L98s came with forged pistons as stock items. If this is the case, replacing your old pistons with OEM units will keep yours costs down. Approaching a rebuild with the mind-set to only replace the weak-points with stronger alternatives will go a very long way in helping the engine live a long life as a daily driver and will not require any sort of retuning. The best part is, it will give you a solid base for any future modifications since you'll know the foundation will be solid.
TheCorvetteKid is offline   Reply With Quote
Old 01-24-2011, 11:53 AM   #13
THE 383 admiral
CF Senior Member
 
THE 383 admiral's Avatar
 
Member Since: Sep 2010
Location: East Nassau NY
Default

Why would anyone suggest a 383 on a TPI setup ( a huge waste of money )
the intake is all wrong for that power and flow

he said not alter the ECU (I'm guessing he meant eprom tune)
a 383 would need all upgrades Injectors, fuel pump, eprom tune,
heads, a small based circle cam to clear the 3.75 stroke
pistons you should use forged and so on

Last edited by THE 383 admiral; 01-24-2011 at 01:51 PM.
THE 383 admiral is offline   Reply With Quote
Old 01-25-2011, 12:33 AM   #14
vader86
CF Senior Member
 
vader86's Avatar
 
Member Since: Sep 2001
Location: Madison AL
Default

Balancing/blueprinting, maybe boring it to a 355. Upgrading weaker parts like rods or crank (which I don't think is really necessary if youre not doing anything to really upgrade power). Porting of the heads and intake manifold, 1.6 RR.....

If you don't want to change the cam, which generally necessitates a chip change, then theres not too many things you can do to the inside of the engine to give outrageous power gains. A little here and there is what you'll get.
vader86 is offline   Reply With Quote
Old 01-25-2011, 07:21 AM   #15
The Bus
CF Senior Member
 
Member Since: Dec 1999
Location: Venetia,Pa,USA
Default

LS engines the only way to go.

Better HP
Better mileage
Less engine weight
The Bus is offline   Reply With Quote
Old 01-25-2011, 09:56 AM   #16
stevie1dr
CF Senior Member
 
stevie1dr's Avatar
 
Member Since: Jun 2006
Location: Miami Florida
Default engine rebuild

Quote:
Originally Posted by SkipRiggs View Post
Hi Folks, I have a 90 L98 Vette. I'll state my problem first; I am going to take my L98 in for a rebuild and before I make that big jump I would like to have some of your suggestions for improvements. Some things I thought of were timing chain and oil pump. I would like some performance mods but I don't want to alter the ECM very much. In other words, what can I do with the engine internals only. Thanks so much for your help. Skip, 90 L98 Vette, 91 ZR-1 Vette
Here's my take on your question:
First off, you need a plan starting with a budget. It's real easy to get carried away once you start the re-build and begin to look at parts and accessories. If you motor is just tired and with excessive mileage, get a basic re-build, ie, rings, oil pump, valve job, timing chain,etc., and maybe a slightly better cam and 1.6.1 rocker ratio increase, to go with the build. This won't require any ecm mods and you will end up with a nice fresh motor with a little more pep.


As fare as mod's go, there aren't many that will boost performance much without dropping more and bigger bucks on that build. One thing that will give you better performance and a good boost in the seat of the pants acceleration would be to change the rear ring and pinion. If you are currently running with a 2.59 rear ratio, go to a 3.07 or 3.45. The throttle response will be much improved and very noticable. Personally, I like the 3.75 I put in my car. You can often find a complete differential on this site at a reasonable price, or buy a new ring and pinion and have it installed.

If you are not going to do the engine build yourself, I highly recommend Carolina Machine Engines in Johnson S.C. ( www.cmengines.com) , as they do excellent work with a good warranty, and are very reasonable and quick. They did mine and the entire build only took 3 weeks including shipping the block back and forth.

Good Luck with your build!
stevie1dr is offline   Reply With Quote
Old 01-25-2011, 11:42 AM   #17
BlackHarleyMan
CF Senior Member
 
BlackHarleyMan's Avatar
 
Member Since: Jan 2006
Location: Winchester Virginia
Send a message via AIM to BlackHarleyMan Send a message via MSN to BlackHarleyMan Send a message via Yahoo to BlackHarleyMan
Default

Parts and pieces purchased from members on the CF:

Used 383 rotating assy -
Cast Scat 9000 crank
Scat 5.7 I beam rods
Used LPE 219 roller cam w/new stock roller lifters
1.6 ratio Comp alum body rockers
Accel Super Ram Plenmum and runners w/Eldebrock Hi-Flow base (limited port and polish).
Old style AFR 195cc race ready 70% CNC ported cyl heads.

Something that I had laying around:

96 Vortec 5.7L truck short block that turned out to be a 2bolt and Will put 4bolt caps on it.

Bought new:

KB/Icon forged PN 9926 pistons (18cc dish)
Hastings Plasma Moly ring set
King Accular brgs
I had a new old stock Melling M55 (heavy casting) oil pump
PBM fluid damper
Rollmaster timing chain
TFS 7.150 5/16 .080 wall pushrods
Victor Reinz gasket set

Clearance worked out to:
.002 Main
.0025 Rod
.007 Thrust
.003 Piston to wall
+.005 piston to deck (quench .040)
.020 Top ring
.021 Second Ring
Piston to valve -
.083 Intake
.122 Exhaust
LPE 219 Cam was degreed in @ 107 ICL with 112 LSA

Other engine Specs:
Displacement 382.6 cubic inches
Bore 4.03"
Stroke 3.75"
Rod length 5.7"
SCR 10.25
DCR 8.1

As you can see this is a "budget build".

Alvin at PCM for less mail order tune. The car is a 91 with Hooker 1 3/4" long tube headers, Y pipe into a single 3" converter to a Magna Flow cat back, ZF 6spd trans, new old stock Dual mass FW, LUK clutch, 3.45 rear gear, 315/35R17 Nitto NT05 tires on A molds.


336RWHP
400RWTQ
BlackHarleyMan is offline   Reply With Quote
Old 01-25-2011, 01:08 PM   #18
ch@0s
CF Senior Member
Support Corvetteforum!
 
ch@0s's Avatar
 
Member Since: Oct 2008
Location: Houston Texas
Default

Quote:
Originally Posted by Pete K View Post
Looking forward to hearing the recommendations myself. This topic does not come up often enough.
ch@0s is online now   Reply With Quote
Old 01-25-2011, 10:56 PM   #19
John A. Marker
CF Senior Member
 
John A. Marker's Avatar
 
Member Since: Mar 2004
Location: Dublin CA
Default

Your computer can compensate for a head change without the need for a new chip. If you change the cam, then you will need to get a custom chip. The better flow of a good set of heads, better intake or similar modifications do not necessitate a chip change. Only when you alter the cam from stock with higher lifts, change in duration and overlap will you need to change the chip. If you don't agree, ask a good tuner in your area.
__________________
1995 LT1 6 speed - stock.
SOLD to son ** 1985 Coup -ZZ4 balanced, LPE 74211 , AFR 180 heads, SuperRam base, runners & plenum, cut out air box, K & N , power coupler, 52MM TB, March pulleys, AFPR, Accel injectors, Walbro FP, 1.6 RR, chip by TJWONG, 160 stat, cut back plugs, 8.5MM MSD wires, custom camber-brace,TRANSGO shift kit, 2400 stall converter, cross drilled rotors, SS brake lines, VBP camber rods, IAS Edelbrock shocks, exhaust, Magnflow cat, 3.07 gears, 13.2 @107.2 MPH in 1/4
John A. Marker is offline   Reply With Quote
Old 01-25-2011, 11:55 PM   #20
GREGGPENN
CF Senior Member
 
GREGGPENN's Avatar
 
Member Since: Nov 2003
Location: Overland Park Kansas
greggpennington
Default

Quote:
Originally Posted by John A. Marker View Post
Your computer can compensate for a head change without the need for a new chip. If you change the cam, then you will need to get a custom chip. The better flow of a good set of heads, better intake or similar modifications do not necessitate a chip change. Only when you alter the cam from stock with higher lifts, change in duration and overlap will you need to change the chip. If you don't agree, ask a good tuner in your area.
I would suggest any modification that requires new injectors needs a tune. I would suggest heads could create that need.

I also wonder if Skip, the OP will even return to this thread. (It's already been 2 1/2 days since his first/last post). And, I wonder if people read his original post thoroughly. John obviously did (though I respectfully disagree with the answer). I'm not sure about everyone else. Vader's reply about balancing/blueprinting sounds more like what the OP might want.

There's not a whole lot you can do w/o a chip change/tune. I'd probably qualify the limit as intake/exhaust improvements. Even then, headers may require adjustment depending on O2 location and accuracy. OTOH, there's nothing that says a stocker can't benefit from a tune. Member "Neat" proved that.

If you're wanting to keep the car/rebuild for a long period, balance/blueprint is a good idea -- especially if the intake/exhaust are upgraded to allow more revs. Otherwise, large runners/base and/or exhaust improvements are about the limit here. I'm not sure I'd even vote for an upgrade in the OEM timing chain or oil pump. Those original parts do a good job compared to the lifespan of other components used in the car.

This particular debate seems more beneficial to address piston upgrade (if any), ring size change, head gaskets, sensors, fasteners, intake gaskets, etc... IOW, the pieces that sometimes cause an OEM motor to fail. Along with that, suggest what minor changes he could install that would REQUIRE a tune.

I'm not sure what Skip means with his comment about not changing the chip "much". WTF...Either change it or don't, Skip! What are you trying to limit yourself to? Changing the fan temps?

I kinda have the same attitude as Pete, but for different reasons. If/where is this thread really going?

GREGGPENN is offline   Reply With Quote
Old 01-25-2011, 11:55 PM
 
Go Back   Corvette Forum > C4 Corvettes, 1984 - 1996 > C4 Tech/Performance
Reload this Page Wanted: Advice on L98 Engine Upgrades
 
 
 
Reply

Tags
219, 383, c3, cam, cheap, corvette, distributor, engine, gasket, gear, horsepower, increase, l98, lpe, matching, stroker, upgrades


Thread Tools Search this Thread
Search this Thread:

Click for Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What Fuel Pressure is everyone running? MikeT 90 C4sixer C4 Tech/Performance 3 07-08-2013 10:00 PM
L98 Questions strc09 C4 Tech/Performance 27 10-23-2012 10:25 AM
Valve Sequence - 1990 L98 heapbigengine C4 Tech/Performance 6 07-17-2012 12:57 AM
the c4 L98 mysterious 245-250 hp Iown1badvette C4 Tech/Performance 9 02-13-2012 01:29 PM
How to bypass the POWER STEERING PUMP at the track! madmatt9471 C4 Tech/Performance 32 06-25-2006 11:36 PM


All times are GMT -4. The time now is 07:02 PM.


Emails & Password Backup