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JHMotorsports inlet manifold and spacers thread
Posted: Fri Jul 02, 2010 11:05 pm
by xyber
RE: JHMotorsports inlet manifold and spacers thread
Posted: Fri Jul 02, 2010 11:40 pm
by marv
Certainly looks impressive!
I'd never have the balls (or the skill!) to do something like that DIY!
RE: JHMotorsports inlet manifold and spacers thread
Posted: Sat Jul 03, 2010 6:12 am
by 1781cc
Kudos to you mate, thats a daring project... I think because of the amount of stuff you have planned for your car you should create a project thread in that section. keeps us posted along the way long after this one gets buried in the pile
Posted: Sat Jul 03, 2010 11:51 am
by infrasilver
Looks good. Keep us posted on how your mods affect the power output.
Have you gone for the heater bypass mod too to keep the intake even cooler or is that just a US mod?
Posted: Sat Jul 03, 2010 12:23 pm
by stumpyrs4
Lovely...
Ask the Mods to make it a Sticky maybe?
Posted: Sat Jul 03, 2010 2:52 pm
by xyber
Right. DONE!!
Roughly 5 hours work, including sorting out a slight cock up and packing up. Very awkward at times and my hands are covered in cuts, but all in all not too bad.
If you engine is like mine give it a good vacuum before and during, I was really careful and still found dust in the valves which I cleaned out with cotton wool and White spirit. So be ultra careful and recheck
The biggest problem is that on the head you have 4 locating pins for the manifold, 2 studs and 2 plastic cones. Both plastic cones had snapped off so just drilled them out, the metal studs were seized in and showed no sign of budging so I took a gas torch to them for 10 seconds a few times. 1 came out, the other snapped off, so drilled that out and them re-tapped the hole with the stud that didn't break. So not bad, just annoying. You then just screw in the 4 longer studs provided.
You then swap over the throttle body elbow and the actuator gear onto your new manifold, fit the gaskets and spacers and your nearly there. Now it's just reconnecting all the vac and coolant lines, elec connections to the from knock sensors and the manifold, seating the manifold and bolting it back in. Then on goes the injector rail, I fitted new o-ring seals whilst it was off.
That's basically it, just need to tidy all the cables back into their positions and your done.
On first startup it you'll notice it revs slot easier and the exhaust does seem to have a little more bark to it.
Just of to get cleaned up and go for a drive to see how it feels so I'll report back later
Posted: Sat Jul 03, 2010 3:30 pm
by 1781cc
oooo, keep us posted, although, will you see much difference before a map?
Posted: Sat Jul 03, 2010 4:37 pm
by xyber
lee_whitehead wrote:oooo, keep us posted, although, will you see much difference before a map?
Oh yes
Went out, got a fresh tank of VPower and went for a play. Considering it is a standard manifold, with so clever smoothing and trickery on the inside, I was expecting the results!!
I love it!! Noticably more torque everywhere and bags of top end!!
The engine revs easier, feels more eager and more punchy, even low down (under 3k rpm) At 3k there is an obvious increase in torque that you can feel pushing you back in the seat and from that point on it just screams right the way to red line!! These cars always feel deceptively sedate untill you look down at the speedo, but now it just feel like its flying!
At motorway speeds, you can be cruising along in 6th, floor it and itll pull like its in 4th or 5th, no hesitation at all!
I just went for a spin on the M5 and was cruising along in the fast lane, when a Mitsubishi Galant VR4, pulls up next to be, dips the clutch and revs, then pulls in behind me. I could see the bloke grinning so I knew what was coming haha
When the traffic eased off he pulled into the middle lane and floored it, I dropped to 5th and did the same and I could hear his turbos spooling up but nothing seemed to happen, but it was me pulling away so quickly he just seemed not to move and all he ended up doing was backing off and giving me a flash
Id say ive gained 2mpg aswel according to DIS, but we shall see in the coming weeks!
I cannot wait to see how it performs with the MRC treatment now!
A highly recommended mod to anyone whos thinking about getting one!
I noticed when removing the manifold that the bolts had hardly any tension on them at all so they may have backed up on their own, so may be worth people checking them just incase. They are the 14, 5mm allen bolts on the outer most parts of the manifold. NOT THE TORX/STAR BOLTS
Posted: Sat Jul 03, 2010 4:41 pm
by xyber
infrasilver wrote:Looks good. Keep us posted on how your mods affect the power output.
Have you gone for the heater bypass mod too to keep the intake even cooler or is that just a US mod?
No, i didnt bother. The manifold is still hot, but now you can hold your hand on it for a while, rather than before which it was almost too hot to touch, if id thought of it I wouldve used my mate laser thermometer before and after to see the actual figures. But the spacers will increase the inlet runners length anyway sotheyll still add torque and they are tapered and port matched to the inlet and head so thatll help aswell
Posted: Sat Jul 03, 2010 4:58 pm
by stumpyrs4
excellent. What costs involved then?
Posted: Sat Jul 03, 2010 5:13 pm
by xyber
Manifold, Ported and polished throttle body, heat shielding underneath, 2 spacers, 4 Reinz manifold gaskets, 14 longer bolts, 4 longer positioning studs, jubilee clips, repainted in factory paint, 8 new O-rings and 8 new pintle caps and a 1hour long installation guide DVD and P&P $1716.35 / £1129.25
Customs fees £231, but I think I got overcharged by £50 going by my calculations so ill claim that back
So £1360, but then you send back you old manifold (shipping back is about £50 with parcels2go) and you get a $500 refund.
By then end itll be £1000 all in, give or take a bit for the exchange rates. Then the cost of a remap
Optional extra - Powder coating in various colours including Red and Noggy Blue
Posted: Sat Jul 03, 2010 6:36 pm
by xyber
xyber wrote:lee_whitehead wrote:oooo, keep us posted, although, will you see much difference before a map?
Oh yes
Went out, got a fresh tank of VPower and went for a play. Considering it is just a standard manifold, with some clever smoothing and trickery on the inside, I wasn't expecting these results!!
Edited due to iPhones being crap to type on and predictive text being too auto edit happy

Posted: Sun Jul 04, 2010 3:42 pm
by nidfix
xyber wrote:
I noticed when removing the manifold that the bolts had hardly any tension on them at all so they may have backed up on their own, so may be worth people checking them just incase. They are the 14, 5mm allen bolts on the outer most parts of the manifold. NOT THE TORX/STAR BOLTS
There was a TSB about that (24.04.02). Even if my car was not supposed to be impacted by the issue I did notice the same thing one or two years ago: a bolt was completely out. Since I got used to recheck them during each service and recently I swapped for new ones stronger (higher resistance alloy) to see if it cures the issue.
The thing is also that the recommended torque is not very high (11Nm), so with the engine vibration it is not much a surprise.
Posted: Sun Jul 04, 2010 7:12 pm
by infrasilver
I have checked my inlet allen head bolts today after reading this and found that 4 of the 14 were slightly loose. I was able to get a quarter of turn from the 4 loose bolts. Worth keeping an eye on.
Posted: Sun Jul 04, 2010 7:33 pm
by xyber
infrasilver wrote:I have checked my inlet allen head bolts today after reading this and found that 4 of the 14 were slightly loose. I was able to get a quarter of turn from the 4 loose bolts. Worth keeping an eye on.
Monitor you start up rattle if you have it. See if with the manifold tightened down it's improved