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Question: Those of you who did power modifications to your L98, what did you go with to add more power?


Jan 1, 2020
Milford Ma
I looked into swapping something in place of my L98 350. Still might go that route with another 350 but right now I’m trying to see what other people did to their engines to get more power. I don’t want an insane amount to start off, but 300 would be a good amount for me. As stated in my previous threads, my 700r4 is possibly blown, I’ll know when I take it out. I hear the pre 86- 700r’s are weak, so I’m also wondering how much power will a stock rebuilt 700 hold from an 85? If I have to rebuild my trans then I will TRY to rebuild it myself which will probably be the toughest thing I’ve ever done, seriously, but if I do add some power I should get a stronger transmission too. Anyway for my budget, I see having about 2k-2500 roughly, after my new trans rebuild. I can’t imagine the cost of stroking it, and the time it would take. Not looking at rebuilding the motor at the moment, but if I decide to I’ll buy a bare block and build that. I hear the stock heads are decent, but I have no clue. But probably looking at some new heads, cam, a super-ram intake even though I’ll lose the low end torque, hollow out the cats, and get a cat back. Then I probably do a general tune up which it needs anyway, probably badly. Also want to get rid of anything in the engine bay I don’t really need, not for power but for simplicity. Let me know what you guys think and if a combination of all this will get me to 300hp. Thanks. Open to any and all suggestions too.
300 hp isn't that difficult, but it will take some decent modifications. Your 85' wasn't exactly the strongest l98, so it will take more than say doing this with a later l98. If you do a set of heads, cam and mini ram you'll be there. I went through TPIS out of Minnesota and they were able to guide me towards what I needed to hit my numbers, both hp and tourque. The heads are around 12 to 1400 for the set, cam is around 380, lifters 120ish, mini ram is what's pricey at 1500. TPIS has mixed reviews and are expensive, but I have had good experience with their knowledge. I race mine with NASA so I went pretty extreme. 510 hp at 6200 with a factory block not stroked factory pistons. Aftermarket rods, lightened and balanced factory crank and everything else aftermarket including engine management system. You might be able to get that number (300) out of a set of later (90-91) l98 heads. Problem is your rpm will still be limited.
So really, in theory it would probably be cheaper to do a 400 engine swap or possibly build it to a 383 then?
Not really. Unless your willing to run carbs. When you drop something else in, your ecu won't work with it. Then you run into 100s if not thousands of dollars in performance chips or a totally different ecu that you can tune the engine with. If you want to have "cheap" power and only looking for 300 hp you can run a create motor with a mild cam and a decent set of heads and know how to tune a carb and you'll get there and still have the tourque you are afraid of losing. If you want to maintain fuel injection keep the l98 do a compression test to check your rings. If good, run a good cam and AFR or Dart heads, 24 to 26 lb. injectors...You might be able to get away with running stock intake depending on your cam choice and save a few bucks. Then get a performance chip that is programmed for your new parts. It all depends on what you want out of it and at what rpm. There are tons of different combinations. FYI...I do have parts for a later model l98 with ecu with performance chip that previously ran 400+ hp.
Yeah I guess it’d be a lot of work to have to swap ecus and all that. I see a compression test being done in the near future to really see where I’m at. I
think for now I’ll be focusing on an exhaust and maybe headers, as those don’t rely on the health of my engine. If compression is good w all 8 then I’ll look into a cam pushrod/lifter roller set.

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