Building a L15B7

Gavin_Danitz

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I’m considering installing a PRL big turbo kit next year (350-400 hp) but I want to have a built engine prior to doing so. I’m looking for recommendations on what I need for the engine to some what reliably handle the power (connecting rods, pistons, valve springs). In addition, what would need to be upgraded in the fuel system. Please share what parts and brands you would recommend.
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Do you plan on re-using your existing head and block or buying new cores?

The easiest thing to do is get the TSP built block and re-use your cylinder head with ARP studs and Brian Crower valve springs and keepers. You'll get your block CSS'd that way which will hold up to 600 hp.

If you want to build it on your own, JE pistons are probably the only viable choice. You could use 73mm standard bore pistons on a new block, if you are re-using a block you'd want to overbore to 73.5mm (additional machine shop work). I'd personally keep the standard 10.3:1 compression ratio.

As far as rods, you could use BC or Saenz. The tier 1 Saenz will hold the most HP I think but any option will hold the power you're talking about.

I'd also suggest doing the Boundary oil pump gears while you have it all apart anyway.

The OE crank is forged so there's not much else to do there other than maybe having it micropolished.

As far as bearings I don't think there are any aftermarket options right now so best to use OEM, maybe oversized by one increment.
 
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Do you plan on re-using your existing head and block or buying new cores?

The easiest thing to do is get the TSP built block and re-use your cylinder head with ARP studs and Brian Crower valve springs and keepers. You'll get your block CSS'd that way which will hold up to 600 hp.

If you want to build it on your own, JE pistons are probably the only viable choice. You could use 73mm standard bore pistons on a new block, if you are re-using a block you'd want to overbore to 73.5mm (additional machine shop work). I'd personally keep the standard 10.3:1 compression ratio.

As far as rods, you could use BC or Saenz. The tier 1 Saenz will hold the most HP I think but any option will hold the power you're talking about.

I'd also suggest doing the Boundary oil pump gears while you have it all apart anyway.

The OE crank is forged so there's not much else to do there other than maybe having it micropolished.

As far as bearings I don't think there are any aftermarket options right now so best to use OEM, maybe oversized by one increment.
Basically everything I needed to know. Thank you so much
 

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Basically everything I needed to know. Thank you so much
No problem dude. I made the mistake of pushing power before building my block so I am in it right now lol. Check my thread for tips I'm updating as we go, good luck and keep us posted!
 
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Gavin_Danitz

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No problem dude. I made the mistake of pushing power before building my block so I am in it right now lol. Check my thread for tips I'm updating as we go, good luck and keep us posted!
Would it also be a good idea to buy sleeves?
 


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I’m considering installing a PRL big turbo kit next year (350-400 hp) but I want to have a built engine prior to doing so. I’m looking for recommendations on what I need for the engine to some what reliably handle the power (connecting rods, pistons, valve springs). In addition, what would need to be upgraded in the fuel system. Please share what parts and brands you would recommend.
I believe you’ll need pistons, rods, valve springs, fuel system, sleeves, etc.(Some other smaller parts aswell)But most importantly, make sure to beef up your transmission as it is the weak point for the Si(Or any manual 10th gen for that matter) and a better clutch that will hold up. I believe the Type R retrofit clutch will hold up to 500whp but don’t quote me on that. No use of building the engine for more power if the transmission cant hold it. If you ever plan on getting it done for you (Professionally) talk to Emmanuel at NaPerformance as you will find that he builds and tears down the L15B7 almost everyday and makes loads of power out of them. His instagram is @k20z3allmotor if interested.
 
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I believe you’ll need pistons, rods, valve springs, fuel system, sleeves, etc.(Some other smaller parts aswell)But most importantly, make sure to beef up your transmission as it is the weak point for the Si(Or any manual 10th gen for that matter) and a better clutch that will hold up. I believe the Type R retrofit clutch will hold up to 500whp but don’t quote me on that. No use of building the engine for more power if the transmission cant hold it. If you ever plan on getting it done for you (Professionally) talk to Emmanuel at NaPerformance as you will find that he builds and tears down the L15B7 almost everyday and makes loads of power out of them. His instagram is @k20z3allmotor if interested.
I was looking at the PPG gear set but it all adds up :rolleyes1:
 

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Would it also be a good idea to buy sleeves?
Probably not if you aren't going for over 600hp, CSS would be plenty. Even totally un-reinforced blocks are capable of 300-400 hp.

If you do sleeves and not CSS, I know Darton makes them but I haven't seen anyone with them installed on an L15. That would be a significant machining cost too.

And as @FC2 said talk to Eman as you plan this out. I know he makes pretty much the only fuel system upgrade for L15s (about $1900 IIRC).
 

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One thing to add if you build the block yourself. You will need to notch the block so the rods won’t hit. Everything everyone has said is pretty much it. Eman has a fuel system upgrade. He’s really the one to talk to honestly.
 

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No problem dude. I made the mistake of pushing power before building my block so I am in it right now lol. Check my thread for tips I'm updating as we go, good luck and keep us posted!
build it before you break it :p
 


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Gavin_Danitz

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Anyone know any options for building the trans that can hold 350-400 hp?
 

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Anyone know any options for building the trans that can hold 350-400 hp?
HPD 4th gear set is the cheap option, only beefs up your 4th though. PPG makes a full gear set but it's super expensive and need to find out how to recalibrate your speedo. MFactory also makes a set but its close ratio and you'll be cruising at like 4k RPM in 6th gear lol.
 
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Gavin_Danitz

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HPD 4th gear set is the cheap option, only beefs up your 4th though. PPG makes a full gear set but it's super expensive and need to find out how to recalibrate your speedo. MFactory also makes a set but its close ratio and you'll be cruising at like 4k RPM in 6th gear lol.
I know 4th gear is problematic so I was thinking it’s the only one I need for that hp range. Thanks for the options, planning out a sheet rn :headbang:
 
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Gavin_Danitz

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Is the HPD 4th gear compatible with the 2020 trans gearing?
 


 


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