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Xpz l67/l36

GTP89

GTP89

New member
Let me start off by saying this is my first major expensive build i have done might not be the best but its good enough for me since it will be my DD.
Part list that i have waiting for the car.
XPZ cam & Pushrods
Gen V with zzp MPS
N* TB/Gen V Adapter plate
SD Headers
Double Roller Timing Chain
Borla Catback
65 Injectors
ZZP Modified Rails
LS7 lifters
SLP Intake with GTX Hood
Ported Lim/180 Drilled T-stat
PRJ Wires
Mezeires EWP with harness
Caspers Fuel Pump Rewire
TB Heat shield
Alt Stage 1 Volt Booster

I might be missing some stuff but thats all that i know of for now related to the engine i do have some suspension as well. Things still needed saving up for set of heads and built trans and a wideband plus a dyno.

So the reason for this thread is i want to get opinions on what would be best to run block wise a L36 that is in my 40th right now or a L67?
My question being is it worth it to go with a higher compression block?
Is the gas mileage and Hp noticeable over a L67?
My worry is due to the high compression and non forged internals that it will chip/blow up pretty damn easy with a SC/Cam setup. Keep in mind its my DD and i drive a lot so i really dont like my gas mileage going down too much even though i might make the jump on e-85 at one point. just waiting for more stations. for now 91 oct..

Any help is appreciated i just want it running great and smooth and not worry about chipping a piston going to disneyland or zoo while taking the gf or something lol
 
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So then why are you putting an XPZ in and considering E85 if you care about fuel economy?

Also a cam like that will chew up timing chains in just a couple years or ten thousand miles. Valve seats, valves, valve guides, valve springs will all take a beating as well.

Low compression will be more tolerant to abuse, however it is probably not worth the cost of purchasing an additional engine.
 
If you go with an l26 from 06 and up they came with the l32 rods from what I've read. They are pretty plentiful and you can get full motors for around 300, check car-part.com for local junkyards.

Good looking bulls otherwise, an intercooler would be good too. Got one for sale if your interested ;)
 
matt5112 said:
So then why are you putting an XPZ in and considering E85 if you care about fuel economy?

Also a cam like that will chew up timing chains in just a couple years or ten thousand miles. Valve seats, valves, valve guides, valve springs will all take a beating as well.

Low compression will be more tolerant to abuse, however it is probably not worth the cost of purchasing an additional engine.
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1st. I know my mileage is gonna drop but by doing a l36 block would that set me up closer to a stock l67 fuel economy?

2nd. Just added my double roller timing chain i forgot to add that on the parts that i have.

3rd. As far as the heads go really depends on the cash i have saved for it. But plan on doing 130lb springs and whatever recommendations there is as far as the valves go.
 
Swiggles said:
If you go with an l26 from 06 and up they came with the l32 rods from what I've read. They are pretty plentiful and you can get full motors for around 300, check car-part.com for local junkyards.

Good looking bulls otherwise, an intercooler would be good too. Got one for sale if your interested ;)
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L26 comes with the smallest rods of any SII+ 3800.

Rod strength goes L26 < L36 < L67 < L32 AFAIK.

L26 are powder forged and quite small. L32 are the large powder forged. L36/L67 are cast, with a size disparity as well.

Rod failures with L36 seem to be rod bolt issues. Engine speed related possibly.

Rod failures with L26 seem to be absolute strength. Namely with turbos IIRC.

GTP89 said:
1st. I know my mileage is gonna drop but by doing a l36 block would that set me up closer to a stock l67 fuel economy?

2nd. Just added my double roller timing chain i forgot to add that on the parts that i have.

3rd. As far as the heads go really depends on the cash i have saved for it. But plan on doing 130lb springs and whatever recommendations there is as far as the valves go.
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1) No, its a large cam. L36 block will help, as will 3.29 gears (for city mileage) however I can't see your fuel economy still matching stock levels.

2) Does not matter if its a double roller, it will still need replacing in time. Just something to consider.

3) This is a large cam that is not designed for stock heads. Consider purchasing stage 3 ZZP heads. They will compliment this cam nicely.
 
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Swiggles said:
If you go with an l26 from 06 and up they came with the l32 rods from what I've read. They are pretty plentiful and you can get full motors for around 300, check car-part.com for local junkyards.

Good looking bulls otherwise, an intercooler would be good too. Got one for sale if your interested ;)
Click to expand...

From what ive read A lot of L26 have snapped the connecting Rod Bolts or Rod over all so staying away from them lol

tight as of now on the budget just got my 65 injectors and a 40th spoiler and another 40th car this month so for now a little tight but it is in my plans just not yet ;)
 


If its your DD just get an intercooler instead, maybe a smaller cam with that. Lower compression isnt worth buying a new short block. the L36 internals are fine, the rods are almost the same size as the L67. Higher compression pretty much lets you run less timing to get the same power. Its not really a big power adder.

L36 on top, L67 on bottom.
PISTON_6.jpg
 
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GTP89 said:
From what ive read A lot of L26 have snapped the connecting Rod Bolts or Rod over all so staying away from them lol

tight as of now on the budget just got my 65 injectors and a 40th spoiler and another 40th car this month so for now a little tight but it is in my plans just not yet ;)
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How many documented cases are there really?

I only know of two cases where a rod snapped when subjected to a turbo.

Also whats up with the ported LIM? A ported LIM would not work well with stock heads.

As for the whole forged deally, sure if you're loaded go for it.

However if you tune safely, then you shouldn't have to worry about it.

JoRoW99 said:
If its your DD just get an intercooler instead, maybe a smaller cam with that. Lower compression isnt worth buying a new short block. the L36 internals are fine, the rods are almost the same size as the L67. Higher compression pretty much lets you run less timing to get the same power. Its not really a big power adder.
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This guy, right here.
 
JoRoW99 said:
If its your DD just get an intercooler instead, maybe a smaller cam with that. Lower compression isnt worth buying a new short block. the L36 internals are fine, the rods are almost the same size as the L67. Higher compression pretty much lets you run less timing to get the same power. Its not really a big power adder.
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Keep in mind that as of now paying for a engine doesnt matter, i have both a l36 in my 40th and a l67 sitting in a pallet at my dads place so im not buying it, i have a friend that works at a junk yard that as long as i trade a block in as a core he lets me pull one for free out of the junked gtp or gt.
 
matt5112 said:
How many documented cases are there really?

I only know of two cases where a rod snapped when subjected to a turbo.

Also whats up with the ported LIM? A ported LIM would not work well with stock heads.

As for the whole forged deally, sure if you're loaded go for it.

However if you tune safely, then you shouldn't have to worry about it.



This guy, right here.
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I have no idea all that i know is that ive seen more L26 snap easier then the L36.
Ported up top still havent ported the outlets till i have the heads done pointless if i do without ported heads.
Thing is i have never boosted a N/A block which is why i ask and how delicate they are with boost.
This is the engine i have on my other gtp with the ported lim.
7f6a7e09-1.jpg
 
They take boost and like it. Just take less of it, and still make similar power. Also takes a larger pulley to produce the same boost/power levels.

All good fun.
 


matt5112 said:
They take boost and like it. Just take less of it, and still make similar power. Also takes a larger pulley to produce the same boost/power levels.

All good fun.
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Just my worry is that idk how delicate they are with boost and if any KR will chip it easy? as of now stock on my 40th with just a slp intake is getting peak of 10KR and 3-6 at normal.
 
Sorry to go off topic here but Matt I thought the l26 in 06 started getting the good l32 rods that gm had left over?
 


Look at my picture i posted of the rods. L36 probably isnt quite as strong as the L67, but hell its still a 3800. Youre not going to break it if you tune it right. Ive had up to 16*+ KR at low RPM and my motor is still fine. Ive also had 22+ AFR at idle and its good. You wont break it if you tune it right. That being said...If you have a free L67 short block and the motor is already out of the engine, just use that.
 
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So stick with the L67?
The extra hp and gas mileage wouldn't be much worth it on a DD with the L36?
The L67 i have sitting.
cdf7a100.jpg
 
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