Jamo's RB25DET ''250Z''

[luvemfast]

I'll swing by next week if that suits.

Just because I'm a nosey parker and want a look 

[jamo240]

Here you go lads...not a very long vid, and early on in the tuning process, but you get the idea...

 

[Agno]

Awesome work Jamo, shotgun a ride!

[Roberto]

Luv the wheels. Luv the paint colour. Oh yeah engine is pretty good too

[Scando]

Nice work Jamo!  I like the sound they make with small exhaust housings.  Sounds like a 747 taking off 

[jamo240]

Thanks boys...I'm happy with where she's at at this stage. I have to get the interior and such cleaned up now in time for the Xmas party.

 

I have decided to do an E85 calibration to see if we can make 300 rwKw, so I will take a full power video of that so you can see it at full noise.

 

Interesting note I meant to point out to other RB'ers too. With my first air cleaner (the one that was losing 15kW at full power), I was getting quite a bit of oil pull over into the turbo inducer from the crank case ventilation. The idea of this pipe is that it is meant to take clean air from after the air cleaner to go through the crankcase and then into the engine inlet manifold (when under vacuum of course...cruise conditions). I imagine I had sufficient vacuum in my inlet duct due to the air cleaner being restrictive that I was pulling crank case air in the wrong direction leading to oil in this duct. I know it doesn't have much blow by, as I took the rubber hose off on one of the full power runs and there is barely any blow by coming out of the pipe on top of the LH rocker cover...something to consider when you design your air filtration... turbos need a lot of air!  For reference, my tuner guy says they would expect to lose no more than 8-10rwKw on cars producing 450-500rwKw, so to lose 15 in 256rwKw is definitely considered restrictive.

 

Cheers

 

Jamo

[TBOWGN]

Awesome thread jamo, I've just read the whole thing for the first time due to recently buying a 400hp + R34 setup for my 76 2+2. so your story is absolutely ideal for me

I'm getting a half roll cage put in for safety and stiffness. Just wondering if you did anything to strengthen the chassis? I've heard they're a bit wobbly with enough horsepower in under the hood... How's your feel?

 

Cheers, Lars

[jamo240]

Hey Lars

 

Glad you like the thread...they're fun to write, and hopefully help and inspire other members with their projects.

 

I did seam weld my car, but I don't imagine it has had a major effect on stiffness. I never did any barwork....to make a substantial difference to stiffness, it has to be integrated right through the car (ie from front strut towers through to the rear), and I did not want to take the car in the direction of being like a race car.

 

On the road, the car does not feel flimsy. I have CV joints in the rear, and the power delivery is very smooth (big prop shaft joints help with this too). The power comes on at about 2,400RPM, and builds quickly such that by 4,500RPM in, say 3rd gear, it will really start to get going and will wheelspin while it's at it right through to redline (7,700 in my case).

 

Cheers

 

Jamo

[TBOWGN]

Good to hear it doesn't then... I'm not planning on doing much else apart from half cage and front/rear strut bars.

Just out of interest what sort of response have you been getting from the public and other drivers?

[jamo240]

Hey Lars.

 

If it's a road car, I wouldn't even worry about the strut braces, but that's up to you.

 

I haven't had a lot of public reaction thus far, but people do look at it as it goes by! The boys at the tuning shop loved it though. They have all sorts of cars through there, and one of them has a 370Z, but they all love the 240Z...as one said, some shapes just never go out of style, and this is one of them!

 

Cheers

 

Jamo

[TBOWGN]

Good man, thats why we're building them... Sorry to harp on but why wouldn't you recommend the braces? And yes it'll be a reliable daily.

[jamo240]

Hey Lars

 

That's ok. Why I am not a big believer in strut tower braces for road cars is two fold. Road cars don't generate the sort of cornering forces required to create substantial body deflection to the point where it is effecting performance. To get that happening, you need sticky tyres up to working temperature and the sort of conditions where you are going around on two wheels. That is not a common occurance on a road car. Why carry around weight and compromise (a rear strut tower brace stops you carrying luggage around in the back as conveniently when on a trip for example) in anticipation of the mother of all corners where you think it might help?

 

The second thing is function. A straight bar across the strut towers is of some use when both wheels are in bump together...in that case, it acts in compression and prevents the two strut towers getting closer together...this is the reason we put one on the Holden Adventra's when we built them...it was in anticipation of people bumping along rough corrugated roads (such as the Gunbarrel Hwy) where such loading would occur, and was included to increase the life of the body shell, not improve handling. Not many Z's are going down corrugated roads!

 

A bar across the strut towers does almost nothing to reduce movement of the strut tower from a torsional rigidity perspective (ie transferring load from one 'flimsy' structure to the other when you're cornering). To increase that component, you need to triangulate the strut tower bar back to the firewall, which in turn needs to be reinforced to prevent it moving (this way you create structures that transfer cornering force deflection into tubes in compression/tension that cannot deflect because of the triangulation). When I was at Nissan Motor Sport in the 90's building the GTR race cars, we had barwork behind the dash board that picked up the triangulation beams that complemented the front strut tower braces. The dash bars in turn were welded to the main cage, which was welded to the body shell, and went through to the rear strut towers. All the tubes were designed to carry loads in tension/compression, never in bending, and that is how the stiffness is achieved. All in all, a very stiff structure torsionally, as well as there to protect the driver in the event of a crash.

 

In my view, a single bar connecting the front and rear strut towers in isolation will offer no discernable value.

 

If your aim is to increase the impression ratio though, then go for it along with those earls braided steel hose fittings that have the hose clamp in them, as race car parts on road cars always have their fans....but, if you are building a road car, be clear about what it needs to do and what it doesn't, and build it accordingly!

 

Cheers

 

 

Jamo

[TBOWGN]

What a reply! Interesting theory, makes alot of sense actually.  And considering ill be jamming a 6ft surfboard in there half the time i might take this on board.    Thanks for the help mate, ill leave this now for more news on your weapon.  Cheers

[Scando]

I agree with Jamo on the strut braces.  I had a front brace built for mine and I couldn't feel any difference on the track, opposed to when we installed the cage which made a huge difference to the way the car felt and picked up 1.5 seconds a lap.

 

The plan now is to add a cross bar between the front legs of the cage in behind the dash and tie this to the gussets that go between the inner and outer fire walls.  We will then build a strut brace which ties back to the same points on the engine bay side of the fire wall.  Is this what you did on the GTR's?  Or were the bars in the engine bay of the GTR's actually part of the cage?

[jamo240]

Hey Scando...good to hear you had a good result with the full cage. You are absolutely right though...cages are in race cars mostly to stiffen up the shell for performance...protecting the driver in a crash is a byproduct!

 

In the GTR's, we had a bar on each side running straight back from the front strut tower through the firewall which picked up the main bar that came off the floor and up the A-pillar and along the roof....this bar came through more-or-less horizontally and welded onto the A-pillar bar about where it bends up along the A-pillar. There was then a bar behind the dash board that had a bend in the middle in the centre of the car and was welded to the A-pillar bar where the longitudinal one came through from the strut tower. Then, there was a bar on each side that came back diagonally from each strut tower, went through the firewall and was welded to the bent one behind the dash board. Finally, there was a removable bar across the strut towers. In this way, the whole lot was triangulated and prevented any movement in the strut towers, and of course transfered the loads between the bars and right through the roll cage and body structure.

 

The cars were very stiff...even driving them through the pits over spoon drains you could feel how unyielding the body was compared with a road car.

 

 

Cheers

 

 

Jamo

[Scando]

Good to hear I'm on the right track.  I know it's a completely different shell but I guess the same principles still apply.  I did want to run bars from the strut towers back to the bar behind the dash and weld them in as part of the cage, the same as you did on the GTR's, but the new CAMS rules won't allow it so I'll have to settle with the 3 point strut brace.  I could do it if I went through the roll cage certification process but that's a pretty expensive exercise.  I can still do bars from the strut towers back to the front legs which may still be an option.

 

You're right about cages being more about performace than safety.  Although now I have a baby on the way I'm thinking a little more of the safety side of things.

[KatoKid]

Went for a ride in the Jamomobile today........... many levels of awesomeness happening here!

 

Engine bay looks very factory apart from the pod filter...no blingy cop bait stuff here.

 

Starts and idles like you would expect a late model EFI car.

 

Power steering is awesome....silent, well weighted and good ratio. Had a drive around a carpark and in my mind its perfect.

 

Engine is well mannered, tractable and as torquey as you would expect a 2.5 litre to be..........and then it comes on boost with a beautiful rush. On cold tyres I wasn't ready for the snap sideways but once the tyres got some heat and grip it just accelerated like a train.

 

Car has a killer Porsche front and Comondore rear combo....overkill for the street but would be perfect for track days.

 

I was very close to doing this swap but with an RB30/25 combo. After going for a ride in this car I don't see the point in the bigger combo. The 25 has more than enough for the street.......you just couldn't use anymore.

 

Well done Jamo, a very refined and effective end product.

 

 

 

[jamo240]

Why thankyou for the kind comments Dave...it's nice to have your work independently assessed!!

 

On to other things though...with the mechanical work mostly done except for a few tidy-ups, it's time to sort out the interior. I have settled on door mounted speakers, so I have been working on grafting a Commodore cable grommet/conduit (the one that goes between the A-pillar and the door, through which the cables go), into the car. At the same time, I decided to go with tweeters as high as I can in the door panel, and mid-range speakers lower in the door. I may install a sub later if i decide it needs it.

 

Given I decided both to cut up the door card as well as re-trim it, I decided it was a waste to buy new door trims just to cut them up, so I repaired the old one in preparation for the mods. I will mount the tweeter in the door card itself, because it is light enought to do that, but the mid-range speakers are too heavy, so I will glass up a mount to angle them up and back as far as possible. The mount will be fixed to the inner door panel, and I will put a hole in the door trim to let it poke through. I will then glass a corresponding shape in the door card which I can trim around, and finish it with a mesh panel built into the door trim, rather than the clip on 6" diameter ones that look a bit 80's these days.

 

Here are some pics of the door card restoration. I made a jig up to clamp the card to, with the shape of the lower area built in to it. I then fitted up 3mm MDF which I then glassed in place. I prefer MDF over masonite as it tolerates water better, but can still be stapled when you re-trim it. The jig is finished in spray putty and waxed with releasing compound so that the glass resin won't stick.

 

CHeers, Jamo

[Cozza]

Hey Jamo, looking good! Can you post a couple of pics of the wiring grommet from the pillar to the door please, also what model commodore it is from. I have been thinking about doing this for a while now but didn't know where to get the grommet from.

Cheers

Mick

[jamo240]

No worries Mick...I am leaning toward the rear door conduit from a VT-VZ Commodore. Unless you have a contact at a OEM harness maker (like Australian Arrow), you need to go to pick-a-part, as the mainstream wreckers don't want you to ruin a harness to get them.

 

I will do some pics and keep you posted on the one that fits best.

 

CHeers

 

Jamo

[jamo240]

OK gents...tweeter location got sorted overnight, and here are a few pics to give you an idea...it is kind aimed up and back, although the pics don't really show that depth.

 

I am going to put the mid-range speaker down lower and forward, where they always go on Z's. I was going to mount it on the door frame and have the speaker poke through, but given how the stiff the door card has turned out with the fibreglass reinforcement, I am now considering glassing the mount into the door card, and coming up with something other than the round grill over the speaker...I will have a hunt around at pick a part and see if anything appeals! I think I will add an extra door trim clip or two in the area between the speaker and the window winder, as it needs a bit more support with the extra weight it will be carrying.

 

Final job is to line the door skin and frame with dynamat...really improves the sound quality of the finished product.

 

Cheers

 

Jamo

[Cozza]

No worries Mick...I am leaning toward the rear door conduit from a VT-VZ Commodore. Unless you have a contact at a OEM harness maker (like Australian Arrow), you need to go to pick-a-part, as the mainstream wreckers don't want you to ruin a harness to get them.

 

I will do some pics and keep you posted on the one that fits best.

 

CHeers

 

Jamo

 

Thanks Jamo, will definitely make the wiring much neater than sneaking out from behind the kick panel then back in behind the door card.

 

Cheers

[jamo240]

Hey Gents

 

I made a visit to pick-a-part today to check out a few cable conduits to route the speaker cables through. I have included a picture for your viewing pleasure. The three parts in the picture, from left to right, come from:

 

1. (LHS of pic) - 2000 Daewoo Lanos sedan (front doors)

2. 1998 Daewoo Nubira sedan (rear doors)

3. (RHS of pic) - 1995 Hyundai Excel (front doors)

 

I had originally intended to position the conduit between the two hinges, which is a peachey spot for it, except there is too much reinforcement in the door and A-pillar assemblies to go through here, given I do not want to interfere with the reinforcement (I imagine this would be a no-no from an engineering approval perspective, as the door mounting system forms part of the intrusion protection system).

 

So, I am now fiddling with the conduit mounted at the curve at the bottom/front of the door...this area is where the reinforcement ends, and there is a small area on the A-pillar where the other end can go...I just have to get the two positions spot on so the two ends dón't foul each other when the door shuts. At this stage, conduit number 2 is looking the goods. I will post some more pics of it all in-situ when I have it done. Although the position is a bit unconventional, it does have the advantage of bringing the cables through near the bottom of the door, well away from the window mechanism, and actually quite close to where the the speaker actually is.

 

The parts cost me $8 a pair from Imlach's in Centre Rd, Clayton.

 

Cheers lads

 

Jamo

[jamo240]

OK ladies....here is a photo expozay on how to put the rubber belows in your doors for speaker wiring. I fiddled around for a while to come up with a good combo, but I think this one works. The part i ended up using was the one off the 2000 Daewoo Lanos (No. 1 in the picture from the last post). THis one had the right angles and length, and I did end up fitting the body end into the area that is reinforced, but there is a 20mm hole in the reinforcement that you can slightly elongate to allow the grommet to fit. The dimension of the hole at both the body and door ends is 22 x 31mm.

 

You have to remove the door and lower hinge to complete the job.

 

Cheers lads

 

 

Jamo

[jamo240]

And here is the installation complete....