Need basic advice on L98 rebuild
Thread Starter
2nd Gear
Joined: Dec 2001
Posts: 2
Likes: 0
From: Middle River MD
Need basic advice on L98 rebuild
I just acquired an 89 A4 w/ 3.07's from my mother as a gift. The car is in decent shape, but not perfect. Unfortunately with only 116k miles it has developed a knock at idle, especially when the car is warmed up. The oil pressure drops to zero at times, but will jump back up to ~25-30 psi while cruising. I am almost positive it needs new bearings and/or rods. So, I 've decided to go ahead and get a mild performance rebuild, nothing outrageous. About a 50 hp increase is what I am looking for w/o spending a fortune.
I want to drop in a more aggressive cam for starters. The heads are relatively new after being replaced after my brother cracked them by letting it overheat. Are these stock heads worth getting work done to them? Is there anything I can do to the intake to open it up a bit to compliment my new cam? What cam do you recommend for a warmed over L98? Of course I already plan on opening up the exhaust.
I would really appreciate any comments and feel free to add on to anything I have overlooked.
Thanks for your help!
I want to drop in a more aggressive cam for starters. The heads are relatively new after being replaced after my brother cracked them by letting it overheat. Are these stock heads worth getting work done to them? Is there anything I can do to the intake to open it up a bit to compliment my new cam? What cam do you recommend for a warmed over L98? Of course I already plan on opening up the exhaust.
I would really appreciate any comments and feel free to add on to anything I have overlooked.
Thanks for your help!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Need basic advice on L98 rebuild (seafunk89)
Congrats on your new Vette and welcome to the Forum.
Though I've added about 60hp over the stock 240hp value, since you will have the motor apart, I suggest you do heads & cam and maybe a ported Accel intake base so that you can port match heads & base. You've got mail on a combo that should add about 50-60hp.
Your stock #113 heads will support about 350hp and a mild pocket port with bigger valves, etc. will flow to over 400hp.
Check out my site for a nice exhaust setup and other mods that realy wake up an L98.
You might also want to add a shift kit and consider doing my A4 shift gate mod.
Looks like you're going to have a fine summer in your new Vette.
Though I've added about 60hp over the stock 240hp value, since you will have the motor apart, I suggest you do heads & cam and maybe a ported Accel intake base so that you can port match heads & base. You've got mail on a combo that should add about 50-60hp.
Your stock #113 heads will support about 350hp and a mild pocket port with bigger valves, etc. will flow to over 400hp.
Check out my site for a nice exhaust setup and other mods that realy wake up an L98.
You might also want to add a shift kit and consider doing my A4 shift gate mod.
Looks like you're going to have a fine summer in your new Vette.
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
Re: Need basic advice on L98 rebuild (seafunk89)
I would purchase another block and do a complete stock bottom end rebuild.
This way you have no down time with the Vette. When the new motor is ready, you just swap them over a weekend.
If you are looking for 50 HP at the crank, you can get that with bolt-ons.
Vic
This way you have no down time with the Vette. When the new motor is ready, you just swap them over a weekend.
If you are looking for 50 HP at the crank, you can get that with bolt-ons.
Vic
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Re: Need basic advice on L98 rebuild (seafunk89)
Hey, welcome aboard. Glad ya could join us. Pics of the car?
Well, I just re-built my motor recently. Spent around 3 grand for the long block re-build (355). Probably can get more for less on a short or long block allready to swap-in and give your core in exchange. I couldn't spend much so I milled the stock Al heads(that bumps up compression), 2.02 intakes, 1.60 exhaust vavles, 1.6 roller rockers. Crane compucam. My thing was to get as much HP and TRQ as poss while still passing Ca smog test. I figure I DID get about 50 or more RWHP with the re-build. Could probably do a 383 stroker and still pass.
Do you have the emission requirements to get past?
BTW, get forged pistons. I got hyperuetectics which don't like nitrous .
[Modified by 89 Paul in cal, 10:25 PM 1/3/2002]
Well, I just re-built my motor recently. Spent around 3 grand for the long block re-build (355). Probably can get more for less on a short or long block allready to swap-in and give your core in exchange. I couldn't spend much so I milled the stock Al heads(that bumps up compression), 2.02 intakes, 1.60 exhaust vavles, 1.6 roller rockers. Crane compucam. My thing was to get as much HP and TRQ as poss while still passing Ca smog test. I figure I DID get about 50 or more RWHP with the re-build. Could probably do a 383 stroker and still pass.
Do you have the emission requirements to get past?
BTW, get forged pistons. I got hyperuetectics which don't like nitrous .
[Modified by 89 Paul in cal, 10:25 PM 1/3/2002]
Team Owner
Joined: Sep 2001
Posts: 62,140
Likes: 1,728
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Need basic advice on L98 rebuild (seafunk89)
Your heads are good, have them ported though. Replace with the better pistons, rods, etc. Your intake is not that great however, you may want to look at the TPIS BigMouth Manifold and then port match everything. In the future this can be used as a SuperRam base. For an aggressive cam, look into TPIS ZZ-9 or Accel 74219
