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b21ft rebuilding

JTF

JTF

Member
Joined
Dec 5, 2022
Been back only a few months now on here, and saving up for a rebuild of the engine 1984 242t b21ft w 300k. I know theres a bunch of threads and discussions that have been done, if you can throw them my way id appreciate it. Basically for now all i have in mind is oversized, forged pistons and see where it goes from there haha. Got 1.2k in the rebuild fund for now, been told might be around 3-5k. Heard redblocks can handle around 350hp? Im not mechanic i won't be doing much myself on this one i think haha
 
dl242gt said:
Nice to see someone rebuilding a B21FT. For my rebuild I bought the Wiseco pistons and the H beam rods. Also you can upgrade the block to squirters using the JohnV kit.
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sick sick taking notes 🙏
 
Are you staying with Kjet? If you do it's a lot of work to help it support your hp goals. Will be much easier to get there with efi of some type. You also want to upgrade to the 90+ exhaust manifold and open the outlet hole up to better match the turbo inlet.
 
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Get a stand alone for sure. I did that and slapped a big .63/67 turbo, big injectors, 90 plus manifold, b230 intake, do89 intercooler, and radiator. Run it on e85 with almost 30psi of boost on a stock block amd head. It's pretty fun. Oh and cd009 transmission, g80, sticky tired and bne suspension.
 
dl242gt said:
Are you staying with Kjet? If you do it's a lot of work to help it support your hp goals. Will be much easier to get there with efi of some type. You also want to upgrade to the 90+ exhaust manifold and open the outlet hole up to better match the turbo inlet.
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oh yea i remember about the +90 exhaust!
and def upgrading from kjet too.
Curious about dimensions of pistons to go for.
 
volvosruinedmylife said:
Get a stand alone for sure. I did that and slapped a big .63/67 turbo, big injectors, 90 plus manifold, b230 intake, do89 intercooler, and radiator. Run it on e85 with almost 30psi of boost on a stock block amd head. It's pretty fun. Oh and cd009 transmission, g80, sticky tired and bne suspension.
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shopping list right there, thanks guys much appreciated as usually 🙏
 
JTF said:
Montreal 🙌
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Gosh, that’s a whole nother country inside a whole nother country.

Was asking because I have a long block with half as many miles that I’m probably not going to do anything with. Sounds like you’ve got power goals though. Didn’t mean to derail, carry on.
 
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JTF said:
shopping list right there, thanks guys much appreciated as usually 🙏
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I don't know if I would recommend the trubo size. It would be good with a slightly smaller exhaust side. Which I can get. It's a turbonetics. It's doesn't wake up till 3,000 rpm bit when it does its crazy! I fo wish I had a bit more compression. I need to get a head shaved.
 
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thanks bouncing ideas, i wasnt even thinking about which turbo yet, sort of cherry on top, but def looking for harmonious chaos altogether 🤣
 
Sourwould said:
Gosh, that’s a whole nother country inside a whole nother country.

Was asking because I have a long block with half as many miles that I’m probably not going to do anything with. Sounds like you’ve got power goals though. Didn’t mean to derail, carry on.
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it is man it is haha, no derailing here man just open conversation 👍
 
I'll be buying the parts for the rebuild here and there over time, i wonder if some parts can be added ahead of time or just get it done all at once, to not mess up the engine chemistry too much
 
volvosruinedmylife said:
I don't know if I would recommend the trubo size. It would be good with a slightly smaller exhaust side. Which I can get. It's a turbonetics. It's doesn't wake up till 3,000 rpm bit when it does its crazy! I fo wish I had a bit more compression. I need to get a head shaved.
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Deck it instead. Tight squish is where it’s at. And for power, low compression. More push longer, less pressure drop through the downstroke. But high static compression with low pressure is a driveable street combo.
 
I went with pistons that give the engine 8.5:1 as a nice compromise to being able to boost a lot and have better off boost economy and performance than the 7.5 stock compression.

I was surprised that high compression with boost seems to be the way car makes have gone. The BMW N55 for example are 10:1.
 
awesome, glad to get details, and numbers, i was going blind now im getting a much clearer picture thanks 🙏
 
- K-Jet, or LH2.2, or LH2.4, or standalone? LH2.4 gives you some chipping capabilities for common upgrades. Standalone supports most anything, except passing emissions.
- Are you wedded to the B21FT? If not, you'd be better off finding a good condition low mileage B230 NA block and adding the turbo oil feed&drain.
- Find a supplier for pistons and rods before going very far. A high mileage B21FT may need 2nd oversize pistons (93.0mm), and might not clean up at that if it's been abused. The B230T pistons/rods should be more readily available.
- If you do B21FT, you can download the factory greenbook engine reconditioning guide. [Beware: some of the english measurements are wrong; the metric ones were the originals and are OK.]
 
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bobxyz said:
- K-Jet, or LH2.2, or LH2.4, or standalone? LH2.4 gives you some chipping capabilities for common upgrades. Standalone supports most anything, except passing emissions.
- Are you wedded to the B21FT? If not, you'd be better off finding a good condition low mileage B230 NA block and adding the turbo oil feed&drain.
- Find a supplier for pistons and rods before going very far. A high mileage B21FT may need 2nd oversize pistons (93.0mm), and might not clean up at that if it's been abused. The B230T pistons/rods should be more readily available.
- If you do B21FT, you can download the factory greenbook engine reconditioning guide. [Beware: some of the english measurements are wrong; the metric ones were the originals and are OK.]
Click to expand...
Absolutely, always have an eye out for a b230, had this in mind it would be ideal, since i could still drive while its getting worked on 👍 lh2.4
Ill download that for sure, i really need to get the inspected prior to rebuild, dont want surprises half way through
 
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