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5 GT Turbo My C1J Forged build

so saturday on way back from santa pod i did some angry logs,

4th gear high boost,
20psi@ 4307rpm
4th high boost.webp
5th Gear
20psi @ 4259rpm
5th .webp


Boost control is still in open loop as i've had issues with the tps signal not being right, as you can see it tapers up to 100% not a sudden 0-100%. Not sure why tho, new sensor, new loom, grounded as per instructions, calibrates and operates fine with engine not running

After the 5th gear run i pulled the plugs and no signs of det but signs of too hot, i fitted new plugs before pod as the old iridiums i couldn't read properly having cleaned them so much in the past.
New br8es got fitted but they still read a little hot, luckily brought a set of br9es at the same time for around £7 a set i'm not complaining lol

In the 5th log you can see the bottom green afr line drop to 10's coming off the throttle, thats the issue i think is slowing me down massively
Hopefully 1psi less fuel pressure (back to 4psi), 1st stage jet change smaller and a good blow out solves it.

Dyno has now been booked for next week wednesday night local to me on a relatively new dyno-developments rolling road so hopefully get some sort of bhp figure i know i wont have Boost plotted but i'll be datalogging at same time so not fussed, will be nice to see what its doing then see how long I can get to try make any more before the owner wants to go home
 
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First run on dyno last night at a flat enough 17psi with a 6500rpm limiter.

Had boost control issues as couldn't get over 20psi on dyno using boost duty number that give 24psi on the road, having felt the solenoid I think it got to hot.

65% gives 24-23psi on road. I went up to 85% on dyno but still 20psi.

Abandoned for the night after clearing up some very slight knock coming on boost.

End result is 196bhp at 17psi.

Not happy I couldn't run big boost.

Datalogs not helping as to why either.

New boost solenoid maybe change to adaptronic ecu then take the dare devil trip to scoff but 2-3 hours driving with a Sidey ain't gonna be fun lol
 
It's the valve all the american's use from diyautotune for megasquirt

Found the Mac part number so will shop about.

Megasquirt is good but it hates noise, had a ht lead come loose on the coil and my god the ecu was throwing sync loss problems everywhere [emoji23]

Probably need to upgrade the engine earths to fatty cables

I just rewired the megasquirt it's all pretty [emoji849] but adaptronic will mean changing most of it as o doubt the ecu will fit where my megasquirt is inside the bulkhead
 
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Is the boost control working ok on the road ?

I know the first time i had the van on the rr at efiparts Scoff had to load up the rollers more as the first pull did not really spool the turbo properly with the .64 causing lower boost than on the road.
 
It was working right but the solenoid got toasted and thrown about on the dyno after the bracket snapped.
I even know the open loop settings thats how much its been logged on the road lol
55% 17psi
60% 20psi
65% 22-23psi top end with 24psi spike

On the dyno 55% was 17psi, but 85% only gave 20psi so i knew something was wrong

I spoke with the maker of dyno developments, we ran in lock mode 4 which is a "normal" setting.
the guy did say there is a lock mode 4f for turbo cars, which is quicker run so less heat into coolant system.
looking over datalogs of road and dyno, the rpms rise too fast. very consistent but either way too little load.
There should be a mode where we can adjust the load so the logs match road/dyno, finding it tho will take time.
Might just road tune it with my brother driving it.

I've ordered a mac valve from scoff and spoken about an adaptronic ecu, but due to numerous purchases i cant afford it atm, I've brought exhaust parts to turn my 2.5inch sidey into a 2.5 inch rear exit with 3inch out rolled tip.
 
I've been told to load the dyno differently so logs are closer to road logs

Having to sort carb out atm,
The overrun richness is still present but not as bad, I think the carb top had eroded away slightly,

Hard to explain but the top has a small raised section to help seal, around the idle jet feed/carb bowl/accel pump jet curve it had eroded away to very thin
Swapped the top for a better one but also found numerous curved sealing edges in the body are tatty tried cleaning them up with dril bits the same size and using hand twisting force to clean up

Hopefully it works, the car has a full tank of fuel to use [emoji58]
 
Carb is being a right pain in the arse.
Took it out tonight to start making sure the boost is ok and to see what my new 2.5 inch rear exit sounds like.

Drove fine going out, then started the whole lean off boost cruising stutter when coming back onto the throttle from overun.

overrun afr is 12.3-13.4, then as soon as you touch the thottle its goes off the aem lean then swings eventaully back for 14-15's or into boost if hold throttle open.

mixture screw isnt snapped.
idle jet is clean and using old style idle jet seal,
accel pump isnt blocked, and set 5-7mm
idle is 14.3afr
boost side fueling is lovely.

coming home car starting running really lean on cruise, even with choke fully on i could only get 16.6. pulling into services idle jet out, clean when looking in headlight blew through it anyways, drove home fine with the usual lean stutter.

I'm wondering if the carb just cannot cope with the sudden rush of suction from the raised comp, big valves and porting.
Whatever it is causing it is making me want to sell the car, ive brought some jenvey throttle adapters from greece (thats if they turn up) otherwise it's stock manifold injectors time
 
Might be worth pulling the carb to bits to check there is no shite in the main jet/emulsion tube etc. I have had this issue on a few carbs and struggled to get to the bottom of it
 
Yeah I've done all that which is the annoying thing

Fuel pressure now back down to 4psi aswell

Going to gap the plugs to 0.6 then swap the enrichment block with another and use a standard 2nd screw body part

Otherwise I might have to find a semi good body all my spares ain't that great with dodgy venturi's [emoji58]
 
the sudden rush of suction from the raised comp, big valves and porting.
Unlikely, the pressure wave created by snapping open the throttle is supersonic anyway, and why you use MAP prediction on EFI as the MAP sensor can't react fast enough to enrich it. The GT carb has mechanical compensation for it with that little squirty jet that pokes out into the carb body. Is that working?
 
Took carb off tonight and scarily found fuel in the leak off pipe on the 2nd stage and I was giving it some the last time it used it.

I've been looking at the exploded diagram of the channels for days.

There's a air hole in the carb top for a channel in the idle circuit, that same channel is also fed via centre of Venturi, then it goes through the brass bush in the carb body before the idle jet

I'm wondering what it's purpose is, mostly because I might drill the little 0.7-0.8mm hole out larger.

I do wonder if the carb is sucking fuel through the progression slot on idle not sure why tho other than idle to high, but it's not that high maybe 900rpm
 
The air hole in the carb body above the idle jet needs to stay stock size unless you plan on messing about with idle jet sizes.

Many years ago i had a 300duration cam in the van. .45 idle jet was too small and .5 was too big forcing the mixture screw to the end of the thread to get a decent idle afr. I did not have a drill for .47 so i used stock idle jet and restricted the air hole with a piece of wire bent 90deg and sandwiched between the gasket and carb top. The restriction worked great and put the mixture screw into the mid range so it did not pop out. No other fuelling changes apart from idle.
 
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Looking at this side profile of the channels, the only real direct place I can be drawing fuel through on overrun would be the progression slot in theory as its effectively only metered by the jet and not the mixture screw

I need a new gasket kit again as only got old 2nd stage seals left
 
So these turned up after weeks of not expecting them too.

Unused C1J Jenvey adapters for DCNF bodies
Each DCNF from jenvey start from £260+vat to £290+vat.
So clearly I'm not going that route, unless some come up cheap plus individual bodies will be a knob on a c1j to setup 100%.
Which means i'll be buying a few flanges somemandrel bent aluminium pipes, injector bungs, plenum box and a single throttle body, thinking of a middle entry plenum but i know a side entry is better for each cylinder, looks vs function problems atm
 

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