Thank you to the forum for allowing me to join and post this message. I hope I can be some help to others who are looking for an answer.
My car is a one owner convertable/ hard top. I like to drive it like I stole it at times or just cruise with the top down. It has AC, new radiator, and is an unmolested survivor until now. I am rebuilding my 1990 L98 after the # 7 head gasket finally let go. It only had 190,000 miles on it.

I would like to hear your thoughts and advise on my build. What kind of numbers do you think it will make.

I am building this engine for torque. I'm keeping the TPI and I rarely ever turn it over 5,000 RPM. I have all new internals - Scat crank, new cast pistons, shot peened X-beam rods,new roller lifters, reworked 113 heads- .008 shaved, 1010 Felpro head gaskets, alighn bored mains, decked .010, honed with the torq plate, new timing set, true dules with H-pipe. I have new Bosch III injectors from Jon. THe only internal parts that I'm using from the origional engine are the push rods and the lifter spider. Here is the Howards cam specs.:
HRS-180225-12



Cam Style:Hydraulic roller tappet

Basic Operating RPM Range:800-4,200

Intake Duration at 050 inch Lift:207

Exhaust Duration at 050 inch Lift:213

Duration at 050 inch Lift:207 int./213 exh.

Advertised Intake Duration:260

Advertised Exhaust Duration:262

Intake Valve Lift with Factory Rocker Arm Ratio:0.450 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.465 in.

Valve Lift with Factory Rocker Arm Ratio:0.450 int./0.465 exh.

Lobe Separation (degrees):112

I have the Auto Trans from Bossier City, LA PATC Raptor 700 hooked to a 2400 stall converter. This is one stout 700R4. Stock 2.59 rear gear.

 

As a 10 year Cf member, I guess I was expecting some input on what pitfall I might look for from the experts here. There is some great knowlege here for sure.
It looks like I'm not going the popular route on this rebuild. Keep in mind I'm not building a high RPM, maxed out HP engine. I want torque. This engine will have a tight quench, a little better cam and low restriction exhaust. Unconventional ? maybe, but that is what the TPI does well and that's what I'm wanting to capitalize on. It still a 350 CI and no headers are going to be used. For the additional cost to upgrade all of the intake, engine internals and exhaust I would be better off to drop in a LS engine and be done with it. The L98 is ancient technology compared to the LS platform. To get the L98 to achieve LS numbers costs @ $4,000. Exhaust will set you back $ 1000 to do it right. I think there will be a day when anyone with a high mile C4 will buy a kit to aid the LS install.
I'm keeping the TPI L98 cause I like the looks and how it works. I'm staying with the factory manifolds - bored out flange at the ports to match the D-port heads, no cats, dules with H-pipe, factory style mufflers so there is no drone.
I will keep you all posted on the results but I would like to hear your experiences with any torque builds if there is any out there.
The bottom line is most engine builds use speed parts made for drag racing and such. It is a science to make these parts work for the street driven car. Sure, it sounds great and gives fuel for a great conversation about parts. The GM engineers are great at what they do and their science works. They have EPA restrictions that the racers don't have. The results are amazing when you consider their box they have to work in.
Keep the Wave Alive

 

You didn't mention heads. You need to either get your heads ported and higher rate valve springs installed or just get some new AFR 180 heads. Of course you need to go with a good set of roller rockers as well with 1.6 ratio. One other thing to help with air flow would be to have the TPI base and plenum ported which will help with air flow.

After your build, get a dyno tune performed. A guesstimated mail order chip is a waste. No matter what the claims, they don't know what is going on with the fuel tables without being on a dyno.

One other suggestion is to possibly go with a 3.07 rear ratio vs the 2.59.

As far as your power outcome, I think you can get to around 300hp at the wheels and in the upper (375-390rwtrq).

Good luck

 

I wouldn't say a mail order tune is a waste as long as you can datalog-it'll just take longer. I've used PCM4Less on both the 350 and the 383 and as long as all your sensors are working right and there are no codes I can datalog it and send it back in to be adjusted only costing me the return shipping. Getting a hold of someone close to you who does tunes and is willing to put some seat time in on your car would get you dialed in would also be a great route to take.

I would consider changing your exhaust manifolds-there are a lot of better alternatives out there-even if you stay the shorty route. Of course if you need to meet inspection then you might not want the bother.

 

Do you plan on doing anything with the intake?

 

Pretty mild cam, but with factory heads and intake it'll work fine. You'll have a nice solid/dependable engine based on your part selection. I'd guesstimate hp at the wheels of ~275-285. Torque around 325. Unless you do some head and intake porting, I just don't see it going beyond that.

 

Question, what are Xbeam rods? I've heard of I beam and H beam.

 

Thanks for all of the response and looks.
From an Ebay ad:

"Full set of 8 X-beam Connecting Rods

These are the older X-beam style rods that have been carefully professionally checked, weight matched, marked shot peened and final cleaned and are in ready to assemble condition.

Includes NEW Pioneer HP connecting rod nuts


Very strong and resistant to cracking

Good for heavy duty, marine, higher horsepower and higher RPM engines on a budget.

We can fit these to NEW SEALED POWER Pistons for FREE with the purchase of the pistons and rings"

I have different pistons for this build. I never heard the term X Beam either. These are probably GM stock rods. My bottom end of my original engine was wore out. 3 pistons had the rings frozen and stuck in the lands. They were #7, #4, and #3 .
Strangely, the engine was clean as new with no gunk. Every bearing was wore out with the same pattern of wear.The cylinder walls still had the honing marks.
I'm keeping the plenum and intake the same as factory. I might switch for a better one if I can find a good one that I like. I'm leaning toward the LT1 intake drilled for the distributor and modified for the L98. It seems to be the best gain for the money.
Barry

 

Do you have a picture of the rods? I read the ad. H beams are rods shaped like an H. I beam rods are shaped like an I. Are X beams I beam rods with an X cast along the rod length?

 

This won't end well. Ever hear the phrase "You get what you pay for" ? I'd be nervous about cheap stuff on eBay.

In addition, if you're putting new pistons on the rods, you need to know what you're going to need to do to the bore. Even when you can see the hash marks, that doesn't mean the holes are round enough for just any ol' piston. Not much fun buying standard or 10 over pistons only to find you have to go 30 over.

BTW, here's a pic of an X-beam rod with the other types. X-beams are used by some of the European car companies...Audi, Volvo, etc



BTW #2...Pics of rebuilds are mandatory

 

I just used the E-Bay ad for reference. The rods I'm using are quality pieces. X Beam might just be a local term for the old Chevy pink rods. I will get some pictures of the pieces.
I'm sincerely grateful for the response from all of those interested enough to post replies.
I have to admit, I'm a novice at engine building. There is way more detail than I woould ever know needed to build a successful engine. This is why I didn't want to go for a top HP engine that might not live to see 10,000 miles.

I drive my car and I drive it to the max the road will allow at times. I just want a little more torque to give me the G force and acceleration I like.
A little short story:
I was on some mountain twisties on the way to the Summer race at Bristol, TN in 1998. A '80s Porsche 928 was tailing me pretty hard in the foot hills and then we got on the serious hills. It was appareant that this guy wanted to test me and my old car. As we got on some curvy roads the driving was very spirited. Keep in mind, we were not street racing; just making to most out of the road. I left that German work of art in the dust on every hill and he would speed up to catch me going down only to be left again as we climbed the curvy mountain roads. We stopped together at a gas station for some race supplies and chatted about the drive. He said that he was pushing his car to the limit just to try and catch me on the climb and couldn't even come close. This is where the torque to weight ratio of the 1990 Corvette became obvious. This is why I want torque. .

 

Nope. They were I-beam rods. "X" rods are as I showed you in the pic above.

Btw...The reason the Chevy rods were called "Pink rods" is due to magnaflux residue that was left on them after testing.

Truth be known, they were good for their time but the new rods are stronger. Technology marches on.

 

Question to Red. If you are going to go with a new crank and pistons, and want max torque, why not just build a 383? It won't cost much more if any, and the 383 is inherently a torque monster with it's bore to stroke ratio. It's a common build, and it can be built for torque or hp or a combination of both. I ran one for years and it was a versitile steet/strip motor.

 

 

That's a good question. I orginally had dreams to go that route. I couldnt find a rotating assembly listed for 1990 L98. Thats not to say that they do not exist, I just couldn't find one. I didn't feel comfortable piecing all of the parts together. You know how it can be, this rod, that piston company, crank X. I do not have the experience to build an engine that I was comfortable with for the initial cost of going 383. I wil admit that I didn't do a lot of research on all of these forums and such. All of these comments are welcomed. I should have trusted my CF Brethren. My decision finally came down to locating parts and the condition of my block - which was in great condition. Boring it seemed like a gamble I was not ready to take. This build started out as a blown gasket repair and morphed into a full rebuild. I was also working within a budget (cheap) that also changed when I changed jobs and got paid more money. Without getting too personal, I am a single parent raising my 2 kids with full custody. My funds are being pulled in every direction away from my car. I saw this as a nickle - and - dime -me -to -death money pit if I went too far from the original engine. I do not have the tuner capibilities that a 383 probably would have needed. My car has been down since June of 2011. It is sitting in my garage on jack stands. I'm also guilty of the "better change this now while I got it apart syndrome". Along with this engine rebuild, I changing the front A4 seal, complete exhaust, rebuiling the starter, new injectors, fuel pump, all filters. Being a convertable, I have to change things while I have the X-brace off the car. Coups do not have this piece. It is held on by 10 bolts. It has to be in the air to remove it properly, and the bolts have to be torqued when it is on level ground. It is a pain. I want to drive the thing and not have to constantly tinker with it. Since owning it, I have changed all of the u-joints, brakes, transmission, radiator, heater core all when they failed. Owning an old car and keeping it running to its potential is expensive. I do all of the work myself. I have paid for the A4 to be rebuilt and the engine. Everything else I have done. It is a labor of love and an exercise in frustration. It is my therapy. Good therapy is expensive. Wave on.

 

I'll assume you haven't bought any parts. A 383 for your situation is nothing more than a new crank and pistons with a .030 over block. Going with a standard bore, you still use a "383" crank but with the smaller bore size you'll end up with a 377. Here's what I would do...

- Buy a "383" crank. The only difference between a 383 crank and a 350 crank is the stoke
- 350s and 383s (aka 377s) use 5.7" rods, so you're buying those regardless. No need to get fancy and go to a 6" rod
- Buy standard bore pistons with the correct pin location for a stroker crank
- You may need to have the shop slightly clearance the block for the added stroke, but this is not expensive and if you're having a shop do other work for you, they may give you a break on price.

The L98 has a 1-piece rear main seal, typical of all small block chevy (SBC) engines since 1986. Since you are not comfortable sourcing parts, call someone like CNC Motorsports and they can set you up with the right crank, rods, and pistons. They can also address the bearings and rings you need as well.

 

I am also rebuilding my 1988 L98. Edelebrock 3860 SLP runners ported gasket matched. Stock heads ported to match. Also ported for better exhaust flow. Hypertext coil. 24lb Bosch fuel injectors. Hedman long tube headers with flowmaster cats/mufflers. Reduced pulley set. Full roller rocker kit and a Comp cam the same as

 

I am also rebuilding my 1988 L98. Edelebrock 3860 SLP runners ported gasket matched. Stock heads ported to match. Also ported for better exhaust flow. Hypertech coil. 24lb Bosch fuel injectors. Hedman long tube headers with flowmaster cats/mufflers. Reduced pulley set. Full roller rocker kit and a Comp cam the same as As long as its red.