Straightneck fitment, Throttle body bore, some "new" info!

[MrMazda92]

So, as I suffer from insomnia and am prone to random tinkering... I took my straightneck IM out of my shop, with the intent to continue my polishing project.

As I remembered having my Curveneck removed from my '93 w/ ZE, I figured I'd throw it on there with a KL01 Throttle body attached. As expected, the throttle body contacted the brake master in the usual spot.

Unexpectedly, the contact was VERY limited, and I'm 100% sure that with a modified K8 linkage and solid motor mounts, a straightneck IM could be used without ever modifying the master/booster. Bear in mind, I did throw on Outlaw thermospacers, which added a slight amount of clearance to the whole deal.

I'll post pictures when I bolt the K8 TB to the manifold(No, I wouldn't ever DRIVE it like that, but the bolt pattern is close enough and I wouldn't modify the linkage at this point. This will happen tomorrow, if I get the rest of my responsibilities taken care of in due time.

If this pans out, then I may go with a KLG4 block, KL31 heads, and a straightneck while I build my other engine. If only there were an oval port straightneck IM

[MrMazda92]

Side note, the K801 TB and KL01 TB use the same TPS, but different IACs(as we already know), but there's something I haven't seen posted previously.

The K8 intake plenum has a diameter of ~65mm, measured at the dividing wall(separates the plenum for each head), as well as the perpendicular measurement.

The K8 throttle body has a bore of 55mm(the throttle restricting plate is 55mm as well), whereas the KL01 TB has a bore of 60mm(we should all know this as well by now). If you can't guess where I'm going with this... you probably don't know me very well.

People use 65, 67, and even 70mm throttle bodies on their KL engines, when stock bore is 60mm... What could possibly be wrong with using a 60mm TB on a K8? Well, if it didn't line up with the neck of the plenum, there would be a problem; As they line up perfectly, I'm going to give it a shot.

[MrMazda92]

Oh, woah! I'm not the only one:
viewtopic.php?f=15&t=73589&p=547524&hil ... dy#p547524

[MrMazda92]

WOAH, More new info! :/

The KL47 Throttle Body has the most material that can be removed(bore enlargement) of all the TBs I have in my possession(K801, KL01, KL47), it's at least an extra 2mm on each side, I haven't heard mention of this elsewhere either...

I wish all of the TB/IM combinations had as smooth of a transition as the KL47/Curveneck, I have ZERO DOUBT that this greatly contributes to the low end torque this manifold offers... At low intake velocities, that smooth transition will no doubt be beneficial.

You learn something new every day, I've learned a lot today...

[MrMazda92]

Okay, so the K801 TB on the Straightneck yielded the exact result I expected. The throttle linkage clears by a few mm, but the IAC collides with a banjo bolt on the brake booster. As the KL01 Tb has a different IAC(it clears, already tested that), I am now 100% sure that solid mounts + a modified linkage would allow a straightneck to be used(at least in this car)

Makes me smile, figuring something cool out that I didn't expect.

[Nd4SpdSe]

What about then the motor torques back under load?

[MrMazda92]

What about then the motor torques back under load?

Post 1...

with a modified K8 linkage and solid motor mounts, a straightneck IM could be used without ever modifying the master/booster.

[Nd4SpdSe]

1sikmx3 long ago just raised up the rear mount to clear his straight neck

[MrMazda92]

How far did he raise it, do you happen to remember? I'll search for a worklog, but I think I would have found it with all of my searching...

Raising it would definitely cause clearance issues with the MS strut bar though, if there aren't any to begin with.

[wagZE]

Nice research.
viewtopic.php?f=15&t=69870&hilit=upside+down+tb

viewtopic.php?f=15&t=77595&p=585503&hil ... tb#p585503


This is another way to get a straightneck in, however the ecu must be modified! Or if you are on standalone it won't matter.

Good research, now figure out how to work with those KL47 ECUs & MAFs in obd1 5 speed applications! Thats a real challenge, I think KL47 was the best design I mean thats why they made the sh1t out of them. They had to of ended kl31 stuff for a reason I think.

[MrMazda92]

Thank you.

I've got a PnP MegaSquirt waiting, I'm a wideband setup away from installing it I'm prepped for VAF delete, and will be running coilpacks with the setup as well. I'm looking forward to this enthusiastically

[Nd4SpdSe]

How far did he raise it, do you happen to remember? I'll search for a worklog, but I think I would have found it with all of my searching...

He kept it a big secret for many many years. It was never posted I dont think, he told a few of us about it near the end. His car was found in a scrap yard in London a few years ago, mx3autozam came across it but he never checked to confirm.

[fowljesse]

If you do solid MMs, and a strut brace like mine, the engine won't move. I put a zip tie on the strut brace shaft to see how much it would move, and it moved about 1mm. That's after several launches. I came to find out that my rear mm was shot. I don't know if it was at that time, but I suspect it was. The strut brace cost me about $30, and some minor fabrication. It's in my worklog.

[MrMazda92]

I'm going for solid front/rear mounts, with poly side/trans mounts. I've seen every page of your worklog Jesse, repeatedly! If the mounts don't keep the engine as still as I'm wanting, I'll be fabricating a bracket for the firewall, and mounting 2 gas struts on the intake manifold itself. I had been on the fence about the solid mounts before, but with the possibility of using a straightneck IM in the air, I'm sold on the idea.

Nd4Spd,
It's too bad it ended up in a scrapyard, that definitely sucks... Either way, I'll figure this out as I go along. If moving the mount is required, I'll be less secretive in my methods... I've kept a few little things to myself as far as plans go, but I am inclined to share anything I have found to be concrete with the community.

Forward progress in a small community comes from sharing information, and I'm all for that!

[wagZE]

I don't know why if you were running standalone you would do anything other than mount the tb upside down on a straightneck. It makes all the sense in the world, then you could bypass the coolant lines that go into it without suffering a weird idle from not having the coolant lines plugged in. Just my 2 cents.

If you are into welding & thinking of doing the strut idea why not add that 5th motor mount on the firewall that mx6s/626s/probes have? Or the one lowerthat millenia's have (probably more difficult to do). If you just add the oem mx6 5th motor mount, sourcing urethane filled for it will not be a problem!