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over View of my 3800 Swap.


z34Phoenix

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Ok. My DOHC lived a long life. Ok since i got my 96 Z34 in 2001 i have gone thru, its original trany, a rebuild, and another trany with a shift kit, higher stall Tq converter, and 3.73 gear swap. in the end it wasn't the trany but the engine that decided to call it quits. the engine jumped timing somewhere on the dummy shaft as all four cams are timed together just not with TDC. It has 224,000 miles on it. I made the decision it wasn't worth trying to re-time it when i could start with a low miles 3800 and trany...

 

i found a low miles l36 and trany from a 98Z. a lucky find. I also picked up a topswap kit. I had a shop do most of the work. i ended up finishing it myself as they shop didn't put it on their priority list. they had it for 3 weeks total 2 weeks of which they only managed to pull the wheels and that was it! i had the car towed home and had it running 3 days later.

 

While the engine was out i beat and cut the fire wall to make room for a set of speed daddy headers.

 

Current setup is:

l36 - FWI, L67 injectors, AP 104's, SD headers, full 2.5" exhaust, my LQ1 Maf installed waiting to get plugged in.

 

Current plans: (ported Heads/IM/GenIII, #105's, 3.8", wideband, lots of timing :-) )

-Im Porting the L67 heads. i currently have the chamber basically done and the bowls started.

-Port the Blower. cut the V out with Saws-all and dremal out the inlet.

-gasket match the heads to the IM

-Im tempted to take the heads to a shop and have a valve job done. i just don't trust shops down here.

-Install Wideband and disable EGR so i can use it as input for the WB signal

-i'm thinking of #105 springs

-depending on how long it takes me to finish porting it all i may go with larger valves.

-then a cam. something to make more top end. i really don't want to do all the supporting mods but XP may be in the future for this engine.

 

Initial impressions of the L36 3.29's vs the LQ1 and 3.73's i had:

-low end pulls a little better. the 3.73s really closed the gap for the DOHC i had

-the engine seems to really loose steam at around 4200 rpm. the DOHC would just start to make power in this area.

-MPG is up 2-3

-it takes longer for the engine to warm up. my guess is the AL heads on the DOHC.

 

here's some videos:

Before:

th_0f97cf87.jpg

 

After:

th_MVI_1153.jpg

 

Here are pics:

 

IMG_1153.jpg

IMG_1145.jpg

 

 

Before:

IMG_1161.jpg

 

 

After:

IMG_1169.jpg

 

some work on the heads:

IMG_1177.jpg

IMG_1187.jpg

 

 

photo2.jpg

 

 

I have the Police digital cluster installed and running and Aeroforce installed:

photo4.jpg

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With some of those mods you have listed, I'm shocked you haveng mentioned an expensive transmission build, and I don't mean rebuild. You're looking at a lot of power there, and a stock 4T65E will not hold up.

 

I'd scrap the valve job. No point to it, and if you want bigger valves, get new heads. That won't be a significant restriction point for a while. I'd look more into an intercooler for that kind of money.

 

Sent from my HTC Awesome using Tapatalk

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the only reason I'm considering having a shop work on them is to make sure they are 100% flat and have a good seal. don't want to pull it all apart for something i can fix now.

 

as for the trany, yes i do have plans down the road for a new built trany. just not right now.

 

I have a feeling that the topswap will make me happy for a while. giving me time to save up for the next phase.

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the only reason I'm considering having a shop work on them is to make sure they are 100% flat and have a good seal. don't want to pull it all apart for something i can fix now.

 

as for the trany, yes i do have plans down the road for a new built trany. just not right now.

 

I have a feeling that the topswap will make me happy for a while. giving me time to save up for the next phase.

 

Unless you have reason to suspect the motor was overheated, you won't have much to worry about. 3800 heads seem to be pretty reliable and problem-free. The old ones on my L27 produced amazing compression test results at 216k miles. I'm talking all 6 cylinders were within 3 psi of each other.

 

Sent from my HTC Awesome using Tapatalk

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  • 4 weeks later...

Ok so my build up of parts is complete. I still have plenty of porting left to do but i figure i'll post up some pictures of what i have so far...

I still have more work i want to do to the chamber and to the intake bowl and then i need to move on to the SC. but got the new valves, SLP rockers and springs/retainers/locks

 

6e.jpg

Exhportc.jpg

 

ExhValvestock.jpg

ExhValveSi.jpg

IntValvestock.jpg

IntValveSi.jpg

 

Springs105complocks.jpg

RockerSLP18.jpg

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  • 1 year later...

Ok time to update this thread. Top swap install had a few hickups/ vac leak, bad ICM harness, bad fuel pressure reg. but after getting that all fixed, it is great! I completed post install tests to check everything. compression test shows 180 psi on all but one cylinder. the other showed 190 psi, 5% diff. Also did a coolant psi check and the system held 17 psi for 45 min without any drop. Vacuum looks great at idle. I have seen a peak of 7.5 psi at 6000 rpm. I had a peak of 3* of Kr when I started tuning and now I am pretty much Kr free.

Here is the mod list:

L36 bottom end

Ported Heads, L76 springs, Manley retainers, Light weight intense push rods, comp valve locks, Si Valves, viaton seals

Port matched Lower Intake Manifold

Ported Gen 3 M90 with stock pulley

Ported L67 TB.

3" MAF from my DOHC

Speed daddy headers to a 2.5" magnaflow muffler and then custom exhaust to dual tips.

4t65e with 3.29's

180* stat

Over sized radiator that is standard on the DOHC

Aluminum coolant elbows

Autolite 104 Iridium plugs .055 gap

 

Ok here are some pictures and a short video of it running:

 

IMG_1635.jpg

IMG_1637.jpg

th_MVI_1639.jpg

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  • 2 months later...

holy bump

 

it depends....with a stock tb...not much...but if you run a LSx/N* tb its required as therre isnt an integral unless you go with the early N* tb.

 

but basically an external maf lets you chose the maf that works best for the intake piping/airflow requirements.

 

minimal gains for an 85mm lq4 with an oem tb asid from making a nice intake/filter setup. gonna need it with a lsx/n* 75mm tb (or SIII since oem ext maf)

and if you wanna go really nuts you can put the 99+ maf into a 4" pipe and make a 100+mm maf

 

hell id bet you could buy a brand new lq4 maf for cheaper than a new/reman oe 3800 maf... so that would be a reason to swap....i just collect good used shit so i dont have that dilema

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yup that track video was with the DOHC. was one peppy setup. my topswap is finally making up for it though.

 

as for the maf, it was a left over from my DOHC setup. i had planned to install a north star tb down the road so i installed it with my 3800 swap. it works great and chances are i will never out flow it, as i had removed the blade and bored it out inside.

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yup that track video was with the DOHC. was one peppy setup. my topswap is finally making up for it though.

 

as for the maf, it was a left over from my DOHC setup. i had planned to install a north star tb down the road so i installed it with my 3800 swap. it works great and chances are i will never out flow it, as i had removed the blade and bored it out inside.

 

What other mods did you do to your Z? I've probably asked before, but on your website the links aren't working. I'm hopefully doing some minor mods this spring, and maybe I'll see what she does on the track

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Well the on the DOHC setup I had:

Fwi - cold air intake

Ported maf

Ported tb

Ported tb arm

Ported lower intake

L67 injectors

MSD coils

104 single plat plugs

FFP under drive pulley

FFP dog bone

Air pump delete and port removed off exhaust

Ported front exhaust manifold

2.5" exhaust from downpipe back with flow thru style magnaflow mufflers

4t60e with trans-go shift kit, 3.73 gears higher stall converter

245/45-17 tires

Plx wide band

DHP powertuner with countless hours of tuning.

 

Yup I think I got it all...

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I think they are the same maf. Shouldn't be very different. My lq1 maf is not stock. I used a 3" hole saw to bore it out. After that I had to do much tuning to calibrate the needed maf table for the PCM.

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  • 2 weeks later...
no still running the stock 96Z disks... never had any real issues with stopping power with the car

 

Holy shit dude! What's happening?

 

Glad to see you're still rockin' the Z!

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