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Jenvey Heritage pinging issue .


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The problem

Pinging whilst setting up new jenvey heritage itb on rolling road

 

Brief story /Engine spec

F54 block with kameari flat top pistons (10-1)

Ported F42 head

Comp cam 480 duration / 460lift

Ms2 ecu (wasted spark /batch firing)

 

Last year I ran the same engine in another car but with a single plenham manifold (stock 280z)

I had the car rolling road tuned but the feeling then was that the manifold was restricting its performance.

The car mapped and ran well 230hp no pinging issues and ran with a normal amount of ign advance

 

The engine is now installed in my new 240z build the engine has been refreshed with a rebore (kameari 87mm street pistons )

I’ve now fitted jenvey heritage itb to a cannon intake manifold in place of the old single plenum manifold and injectors .

On the first rolling road session to set up the jenveys the tuner detected pinging / detonation with his det can sensor attached to the block.

He had to pull out up to 10degs of timing .His initial thought was that I should adjust the camshaft timing from 110 to 108.

But last week when returning for a second session the pinging /det was still there so we pulled the spark plugs on very close inspection the plugs on 3 and 4 cylinder appeared richer.

As it’s on itb you would not expect to see this . So Looking at the manifold the center cylinders intakes are fairly straight where as the outer cylinder manifold tracks are angled inwards.

Heritage itb also have there injectors at a angle 15degs i think ? where as most stock itb the injectors fire straight

What I’ve now found is that the injectors in the two outer heritage unit when injecting fire there fuel which hits the side wall of the manifold about halfway down the track  but the centre unit pretty much fires it’s fuel directly down the manifold missing the side wall

Also when removing the manifold the tracks where wetter than I would

have expected and looking into the cylinders with a endoscopes the piston crown looks wet with bore wash

My tuner says that it’s near on in possible to map it if all cylinders are not equal

Come on guys give me your thoughts and experiences plenty of you must be running similar set ups

   

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1 hour ago, AydinZ71 said:

@Fairlineguy Hey there. Is your cam duration a typo? Just have not seen anything as high as 480. My race cam is at 320 duration I&E (not streetable), and I don't think there is much room to go from here. 

 

1 hour ago, AydinZ71 said:

@Fairlineguy Hey there. Is your cam duration a typo? Just have not seen anything as high as 480. My race cam is at 320 duration I&E (not streetable), and I don't think there is much room to go from here. 

 

1 hour ago, AydinZ71 said:

@Fairlineguy Hey there. Is your cam duration a typo? Just have not seen anything as high as 480. My race cam is at 320 duration I&E (not streetable), and I don't think there is much room to go from here. 

Opps my typo 280 duration 

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Ahhh that makes sense. 
 

yeah I’d check your injectors. When she is up and running, I wouldn’t worry too much about the spray pattern and stress about whether the manifold wall is getting coated. Above idle, the flow and engine heat will instantly evaporate the fuel that hits the manifold walls. In fact, the fuel won’t even get to the walls, it will just get carried straight into the motor with the manifold air flow. Most important thing is to make sure all injectors are CCing equally and consistently. 

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Posted (edited)
4 hours ago, madkaw said:

That’s a tough one . Running a 3.2 and the n42 intake now . 
Did you do anything with the head when you had it apart ?

As mentioned engine was running great in another car with same set up but a single stock plenum.

until the engine through all it’s oil out.

Engine has been rebuilt now with kameari pistons  .35 above deck. But now has jenvey heritage itb.

we removed the spark plugs the centre cyl plugs feed by the centre manifold where clearly running richer.

we swapped them to a different cylinders and ran the car again on removal they where showing richer.

this lead us to the conclusion that the is a mixture in balance and that only the centre cylinder are running correctly .The ideal of itb that all cylinder a receiving the same fuel.

we had the injectors out and tested them on the bench they are all good

Chatting with the tuner he’s having to pull about 10deg of timing out to stop the pinging .

so where on the old ign map it was a 20 deg it’s now at 10degs

I forgot to say the ping is at low rpm open throttle under load at higher rpm the timing has still had to be pulled by a few degs

Clearly there is wetting of the wall of the outer manifolds as the angle of the injector fires directly at it I’m guessing that higher rpm there is enough air flow to ensure it mixes and never hits the wall .

 

Edited by Fairlineguy
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Posted (edited)

Here is a photo of the angle of fitment of the injector in the throttle body .

these bodies a 48mm with 350cc injector.

also can’t help thinking there probably on the large size for 230-50hp I’m thinking it might be worth seeing if I can try a set of standard itb with the injector firing straight,

my question also would be 

what size would be recommended to work well

 and has anyone else found that they need to pull timing out

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Edited by Fairlineguy
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48 should be fine. OER makes a 50mm carb that is significantly more expensive (almost 2X their 47). I would be surprised if you saw a big performance increase from just the increased diameter.

 

Curious, why did you go with ITB’s? I know they are sexy, but I’m not convinced they are worth all the trouble when most folks don’t lighten the engine internals or go with a smaller diameter clutch friction surface to really make the response pop. Is it for the “wow” factor? 

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Posted (edited)
14 minutes ago, AydinZ71 said:

48 should be fine. OER makes a 50mm carb that is significantly more expensive (almost 2X their 47). I would be surprised if you saw a big performance increase from just the increased diameter.

 

Curious, why did you go with ITB’s? I know they are sexy, but I’m not convinced they are worth all the trouble when most folks don’t lighten the engine internals or go with a smaller diameter clutch friction surface to really make the response pop. Is it for the “wow” factor? 

Suppose I could refit the old manifold and injectors and load the old map and see how it runs it’s just a pain having to rewire the old injectors resistors plus it’s not very sexy .

The engines crank has been balanced and has alloy light weight flywheel. I’ve used maxsppeading rods ,electric water pump 

cop ign 

i just hoped the throttle bodies would give a sharper response and finish it off 

Photo of old plenum set up

 

 

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Edited by Fairlineguy
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  • 4 weeks later...
  • 4 weeks later...

Quick up date .

Jenvey loaned me a set of there 45mm bodies fitted up with Bosch 350cc injectors the same as where fitted in the heritage units.

back to the tuner/ rolling road.

Car is now running great no more pinging,plugs are burning equal and ign timing advance put back in

So the heritage units have gone back and I’m running the normal itb 

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