my RB25/S14 progress

[240SX GT-S]

I posted this on RaceBread a little while ago. I was hoping for some feedback, but i didn't really get anything. So I figured I'd try you guys

So slowly but surely this swap is happening. Over my thanksgiving break I dented up my trans tunnel (which involved more denting then Top Hat originaly wrote on their instrustions) The transmission went in quite easily with the new crossmember. But the engine on the other hand, took some tugging and pulling and such. My father and I have come to the conclusion that we are welding the crossmember portion of the Top Hat mount to the cross member. We have one bolt in on each mount, cause two doesn't fit... I guess you have to drill the slot out on the crossmember? Oh well, its getting welded. And a little more on the engine mounts; it looks as if the isolators are being pulled slightly to towards the firewall. Is that okay?Enough chit-chat, here are some sub par pictures.

Top view (sorry about super rusty chain...):

Frontal:

This is how my shifter sits now (it would probably be a better reference picture without the boot...)

And the motor mountsDriver side:

Passenger side

Thanks for checking it out. I still need to clean and paint my engine bay. The motor is coming back out for more transmission tunnel denting and the mount welding and thats when I'll finish that stuff.Any pointers and such are more than welcome!

[NightKids2]

Dude what manifoldis that? Is that a Supra intake manifold?!

[240SX GT-S]

its just the factory plenum with a relocated throttle body. I'll put pictures up (if i can find them) because it seems to be the point of interest. I have to fix it a little because the TB just barely hits my fuel pressure regulator.I doubt I get any perfomance increase from the modification, but it allows for much more logical intercooler piping.

Is there anyone with Top Hat mounts that could give me some feedback?

[240SX GT-S]

No one can give me any insight??

[Darius]

My top hat mounts didn't fit in my S14 quite right either. I had to "adjust" the slot on the crossmember for the bolt holes to clear.

I'm a little concerned with the intake plenum having the throttle body at one end without necking down along the way. It looks like it could cause uneven air distribution to each cylinder.

[240SX GT-S]

My top hat mounts didn't fit in my S14 quite right either. I had to "adjust" the slot on the crossmember for the bolt holes to clear.

I'm a little concerned with the intake plenum having the throttle body at one end without necking down along the way. It looks like it could cause uneven air distribution to each cylinder.

I would have to ream the slot also, but i'm just going to weld the mount onto the crossmember. Sure I can't put in a different motor after, but i don't plan on going back (KA) or putting anything else in. Did you notice any directional preference in the isolators, like mine do? I haven't tightened the isolator bolts down yet. I don't think that will help. But I thought I'd throw it out there.

As for the plenum, what do you mean by "necking down"? I don't really see a problem with uneven air distribution. But you may know something that I don't.

Thank you very much for giving me some feedback!

[97s14pwar]

i was just reading about the top hat mounts. it says for a 97-98 you have to drill out the holes out bigger on the crossmember. welding it too seems like a good idea. ill be ordering my mounts soon, hope everything goes well.

[240SX GT-S]

Did you read that on the Top Hat site? I must have missed that. I wonder why 97-98 are different from 95-96? There should be no difference. Must be no difference because my 95 would need to be drilled out if I went that route.

Thanks for your support

[Carl H]

all s14 xmembers need to be ground for proper tophat mount install.imho the mounts are trash, the isolators are garbage.

[rotorimp]

I looked at all the mounts and bought a Tig welder instead-It may be large $$$$ for the welder-- but Now I can make any thing I want and the welder will pay for its self just on the install alone!!!

[240SX GT-S]

Darius, haven't you been running the top hat mounts for a couple years now? With no problems? I think I specificly remember reading that before I bought them. It kinda sealed the deal for me.

Since I have the honor of having Carl H to respond to my topic, what are you feelings on the plenum modification? You seem to have abundant knowledge, thats why I ask

Rotorimp, smart buy with the welder. With some skill and know-how, you now have the ablity to do anything you want, haha.

[97s14pwar]

yea i got that right off the site. it still looks to be at better route for the money. compared to mckinney mounts

[Darius]

Yeah I've had the mounts installed for over a year, but when I e-mailed them about it, they basically said we've never had a problem with it...aka figure it out for yourself. I've only been driving the car for a month or two now and haven't had any issues with them. I'm sure once you get them in there, they'll be fine and you'll forget about them.

My comment on modifying the stock intake was because it is designed for the air to enter the plenum from the center and fan out to the ends (short distance). By placing the plenum entrance on one end at high air flow rates, it is difficult for the air to make a 90-degree turn and enter the first runner creating a rich condition on No.1. Inversely, the extra air that could possibly back up at the end of the plenum could be forced down runner No. 6 creating a lean condition in No.6. There are also arguements for having constant velocity across the intake runners for even air distribution. Hence, why the Greddy and other aftermarket plenums narrow as they near cylinder No.6. As you decrease flow (being sucked in by intake runners) you must decrease the cross-sectional area to maintain semi-constant velocity.

Hopefully that isn't too long and boring.

[240SX GT-S]

That makes sense. Thanks for the explaination. I tryed contacting a guy that did this to his RB. I wanted to know if he was experiencing any problems with it. But he never got back to me.I've never taken classes on fluid mechanics or anything that would help teach me these concepts, but will the air really have a hard time taking a 90 degree turn? It's air. The piston is also sucking down the needed air, so if there is air in the plenum i'd assume the cylinder will take it. But the build up of air in the back makes sense to me.I'm probably way out of my league with these theories

[240SX GT-S]

BTW, I think it was actually kamin who said he has been running the top hot mounts for awhile now without problems... Sorry, i confuse the two of you from time to time, haha. its the car, the color, the motor

[240SX GT-S]

A little update.

So I dunno if this approach has been publicized yet or not, but I just cleanly cut my radiator support in two places. and unbolted the three supports to create a much easier way of pulling the rb out, and putting it back in. (see diagram) "Ghetto" you might say, "buy some taller jack stands" even. But this looked to be a really good idea. There are other things that provide more structural integrity to the front end of this car then this support, but its going to be put back, obviously. So no worries.



Since this made the whole deal 100 times easier, I feel that welding the thing back in would be sad, yet would look the best (aka un-noticable) I think I might look into bolting it back in... "Ghetto" was my first thought. But I dunno, its makes everything soooo easy. The motor and transmission just slide in and out as one complete unit. What do you guys think of all this?

[Darius]

That was a pretty damn good idea. It would surely make the installing and pulling of the motor a lot easier without the radiator support in the way. Might just want to find a way to fasten it back up with bolts so you can remove it again should you need to pull the motor again.

[240SX GT-S]

Thanks for the positive response I suppose I will look into bolting it back together, but make it look real nice, haha. Form over function right?

[240SX GT-S]

I almost forgot!So when I took the motor out, we were getting ready to weld the crossmember pieces in, we took a look at them. We found that they had some adjust left in them to help us out. And we found that they bent under the load of the motor... That didn't seem healthy. But my dad assured me that with them welded in place, it would help it out. I trust him, but that just didn't seem right.Oh well, they better work, they are welded in and ready to go.