Isuzu turbo diesel tuning guide

[Jack]

Pah, dunno, ran out of ideas a long time ago.

Get some propane burning in the manifold or something. lmao

[KristofHA]

i also think when you have a "low compression" diesel it gets hard to start. Maybee when you get the starting rmp higher, it will start?

I remember in school, we did a compression test on a diesel with a discharged battery and a fully charged battery.
The starting compression of the discharged battery was much lower then when we did the test with a fully charged battery. Mybee there are elektric startengines for isuzu that make more starting rpm? Are you can place 24V on the starter?

[saabturbonova]

if ya use the supercharger off of the toyota mr2 mk1 s/c model, its small and has a clutch like an a/c pump. that will get it going, or a super fast starter, the high torque jobbies and use 4 extra glow plugs in the inlet to warm intake air?

[KristofHA]

find this:

http://www.beru.com/english/produkte/gluehkerzen/gf.php

[DutchNovaDiesel]

The 16V isuzu diesels have a compression ratio of 18,4:1 so (C)DTI flywheel,starter,gearbox and off you go !

Starter comparison:
15D/15DT/17D 9 Teeth
X17DT 11 Teeth
Y/Z 17DT(L)(H) 13 Teeth

[santaclaus]

The usuall trick for tuned low comp diesels is to use 'ether' the main componet of easy start fluid , - ive seen large plant , machines use a special plumbed in canister system - the only thing with ether / easy start is that you have to disable your glow plugs , otherwise the ignition source is enough to start combustion way to early and can literally blow the rings apart if your unlucky - theres lots of fuels that could be used but i cant say im a big fan , i see using excess fuel to start as defeating the object , as all you are doing is using specific substances to advance your combustion timing , ( as they do not share the same properties of diesel ) this in turn doesnt increase compression , ------ other fuel's only allow the engine to be more easily self ignited , -- The engine still has to run with potentailly harmfull timing + fuel , usually smoking like billio until true operating temp is reached where it can then run for its self , not a great for long term every day use , -
Using some form of lag less boost is the most effective method imho , -- a low geared supercharger is ideal , - but parasitic losses are the conn when driving , unless you use a electromagnetic clutch like some air con pumps use - or a like most merc's do on their SC's - abit OTT though ?
- ideally you could use the turbo you already have ( you dont need alot of boost ) , you just need to suppy it with exhaust gas from some thing else - say a small generator / bike engine or perhaps one of those home made jet turbines made from an old turbocharger ????
- or even ? a one of those crap ebay electric superchargers ( it only has to be enough boost for idle )
OR - electric leaf blower through a 12v inverter - the list is end less lol lmao - its just what would be best ?
It wouldnt be so bad if we owned the cdti 16v isuzu like dutchnova says as all direct injection diesel can run between anywhere between 14 + 18 to 1 comp ratios - purely because they dont have as much internal surface to combustion area ratio , absorbing all the goodly combustion heat away , like our large prechambers do , thats why direct injection motors are always more effient , low comp along with low thermal loss ! - but 16v isuzu bits and engines are way too pricey to play with to me
( possibly ceramic coatings may help ??? )

----- The whole things not a major priority for most owners anyways as yet though , because theres no big enough turbo solutions for the engine to warrant it , in those terms , but its nice playing with the ideas

>>> EGGMAN , ive bounced around that same idea too lol lmao- ive all ready CC' every thing ( see earlier post ) and removing or retracting the glowplug would reduce the the comp ratio down from 22 : 1 down to 19 .5 to 1 i think it was ---- dont know how you would retract it too ? its a 10mm thread in though if my memories right if that helps

[eggman]

i know i was thinking of a syringe affare that was down at start up and when boost was lifting- the boost itself would "open/alter" the valve / syringe thing and if it was a canister type thing u could make it as big as u wanted so would have a true variable comp 21- 1 right down to 7 - 1 if u felt the need but u would need to run about 10 bar of boost man and injectors out a 1200bhp cummingslmao

[Big_James]

just a though would swapping the turbo for a supercharger or even compound charging not be viable option for more performance? now please bare with me on my vauge lack of knowladge on the tuning side of things but i do have a TDS astra and im considering having a fiddle as a friend of mine is an opel/vaux enthusiast hes currently putting a 2.5 v6 in to a south african import 180ie saloon atm (mind_crash's Opel Astra 180iE) and he'd be helping me have a play

[santaclaus]

EGGMAN > you wanna work out some proper schematics and patent that mate , before i beat you to it and make my millions , lmao ive honestly seen far crazier things like that on manufacturers concept engines - e.g a cylinderhead that is lifted by rams above the block , giving running variable comp ratios with an ocordian style HG lmao

BIG JAMES > you can do anything
absolutely no reason why you cant SC it , - or even use one in a series forced induction arrangement , aka compounded / twin charged -

simplist is to have the turbo boost blowing into the super charger and then 'that' into the engine , but just remember , if you are compounding then , the item that is being blown into by something else , doesnt actually suppy any airflow of its own - you are only using it to recompress the the air given to it by the turbo a second time ( often called the high pressure unit or recompressor ) , theoretically multipling the pressure ratio

- so duely you have to size the low pressure unit e.g the turbo - big enough to supply all of the air flow required - But its worth noting that , even though this sounds ineffient , you can actually size the low pressure unit way bigger than you would normally be able too for that given engine size , As the supercharger is increasing the capacity for making lots more exhaust volume to spool it

- Rule of thumb is roughly that your low pressure unit (the big one) needs to be around twice the size of your high pressure unit (the small one) -
Making highier pressure ratio's for the same air flow which the HP unit is doing ,----- is advantagous in many ways
- for starters , in a basic explanation , it helps push boost into the cylinders where ordinarly you wouldnt be able to -
e,g most ways in which you would calculate normal turbo sizing requires , finding out how much air flow you need to meet you target bhp - say in either cfm or lb min - and then after wards take into account the size of your engine vs it volumetric effiency and the rpm considered - as this then needs requiring how much boost pressure ( P.R ) your turbo needs to be able acheive to beable to force that amount of air mass into a cylinder smaller than its self ---- ( note boost pressure is only a measure of restriction in the engine not air mass ) e.g if you try and push 10 tons of sh*t into a 5 lb bag , you will make a heck of alot of pressure - >> what you need to know is ,
= is the fan item etc that is suppling the large quantity of air ''capable'' of pushing it in without it stalling the fan its self ??? (e.g the surge line on a compressor map)--- ( remember if theres x pressure pushing air in then theres the same x pressure pushing back at the item suppling it ) and thats why we look for how much boost pressure a turbo can deliver after looking at how much air mass it can flow ! - As an example my engine requires roughly say , 35 lb min air flow to make 250 bhp - thats the easy bit , 100's of turbo can supply that -- but it would require a turbo capable of sustaining 50 psi of force to push it in to my tiny little engine with its micro sized ports and low rev range --- Now there isnt a single turbo out there that can spin fast enough to push 50 psi - ''but'' if you use one turbo to supply the air flow and use it to compress it once then feed that into the intake of another turbo or SC , then you are able to compress that air flow a 2nd time and then be able to deliver it at the engine , where once you couldnt before with a traditional setup

Note not all twin charging , or twin turbos have to be in a compound arrangement , each turbo or SC can blow into the inlet mani from separate paths or through methods of valved routes and be disabled from operation and even brought in at various rpm without ever being fed into each other like compounds - But only by putting them in series and through each other will you gain highier pressure ratio's - It depends on if your application demands a high enough requirement for a certain air mass needing a pressure ratio highier than what can be done normally
the choice is yours

[Big_James]

mmm... that gives me an idea, when i get another job and can afford it i think ill have a go at sticking a super charger and a bigger turbo on my TDS , so if you live around leicestershire, England, keep your eyes peeled for a streak of white lightning lmao

[Hacula]

I was wondering, is it usefull to modify the inlet manifold? Since I have three inlet manifolds lying here (1.7 TD, 1.5 TD and 1.5 D) I could take some time to modify one of them. Or wouldn't it make any notable difference?

[tom_moran]

@jack

oh man of all 1.7 diesel knowledge, i have a question.

i currently have a GM low blow 1.7td in the astra, i want to put a isuzu one in there. i realise i have to change the actual engine block but what else? will the loom etc from my GM one work? im after a rough guide of what i need to purchase to make the conversion.

thanks for your help

Tom

[DutchNovaDiesel]

From the donor you want:

-engine
-gearbox
-driveshafts
-first exhaust pipe (downpipe)
-fuel lines, vacuum lines, coolant & boost hoses, throttle cable
-radiator (& intercooler)
-wiring harness incl. relays
-R.H. side enginemount, needs to be bored/grinded out of the donor and welded onto the chassisleg of your car.

[tom_moran]

really?? bugger, didnt realise that, i thought they were the same. at least as far as the gearbox, drive shafts, radiator and intercooler were concerned

[roaddog]

maybe you could sell your car and buy 1 with a isuzu engine in it ? that will save lots and lots of work.

anyway a update about my car.

the last time I was on here my car had past its mot. but I had a bit of a prang and hit the front end. I bust the front bumper, the intercooler and the front lights. so not good.

I have put a new front end on but have not had time to sort a new intercooler out and as I want to race it I have had to put the old turbo to inlet pipe on that came with the car so now it has no intercooler. it will be good to see what the times are like at santa pod with out it.

I will be at santa pod this weekend if any of you are going. pop along and see me if you want. ( satin black corsa. with the reg m+++ bvv )

also if anyone has a front mount intercooler that will fit on a corsa b with all the pipes ( mine are bent lol ) let me know.

[Jack]

Hi Tom. Like DutchNova says, not a lot of what you've got is actually compatible. It might be worth trying to source an entire donor car rather than trying to find bits separately.

Roaddog... I'm in Wembley Arena tomorrow night so I might pop in on the way down, schedule depending.

[tom_moran]

thats a shame, cause mine apart from the engine is a sound car. no rust underneath, interior is like new, got a gsi interior handles have been changed, de-bumped. so i have the choice of putting a isuzu 1.7 or go redtop. im thinking maybe the latter if the MPG is ok. i thought it would be easy to just swop the diesel which is why i was considering it but if its hassle......................

[LongLiveTheNova]

Got round to doing a few tweaks on my Izuzu astra at the weekend.

Standard it was about 8-9psi, fitted a boost controller, and turned the max fuel screw about 90deg clockwise. It now runs about a bar(14-15psi)
Thats with the boost controller wound fully down(min boost), if i wind it up even by just 3-4clicks it will then only boost to the standard 9psi, not sure why that is? If that safety valve in the inlet was opening then id expect it to hit the cutoff boost level and not the std 9psi?

Also, how much should you adjust the fuel screw? Enough to get smoke on boost?? I cant seem to see any smoke out the back window at all. Would it still make 15psi even if it was running lean??

Im not really "genned" up on dervs lmao
But the mods make quite a nice difference!! Especially in 2nd-4th gears

(ive not removed the white ring btw, as i cba take the inlet off.. And couldnt get to it to cut the ring off with the inlet still on, is that mod really neccessary????

[Jack]

Also, how much should you adjust the fuel screw? Enough to get smoke on boost?? I cant seem to see any smoke out the back window at all. Would it still make 15psi even if it was running lean??

Lean? LEAN?! You mean "under-fuelling!" lmao

Yes, you want maximum smoke. Put it this way... if there's no smoke out of the back then you're not using all of the air up. lmao

[roaddog]

well my car ran ok at the pod but with out the intercooler I had to turn the boost down and it smoked way to much so had to turn that down to.

I did not run with my race wheels so just span the wheels on the start line ( only 185 x 14s astra wheels )

it runs in the very high 14s at just over 85mph in full race set up. but the best I could get this weekend was a 16.8413s @ 79.77mph so 2 secs off.

so its safe to say a intercooler on a corsa is a must.

here is some pics.

the air filter comes of the turbo and when racing I take the head light out and turn the filter round so it comes out the head light ( better air flow )









all in all not a bad day at the pod. but need to sort the car out as its just to slow at the minit.

anyway I hope to see more TDs at the pod. send me a pm if any of you are going.

[LongLiveTheNova]

Lean, under-fueling,meh Whatever lmao

Will give the fuel screw another 90deg

Edit-Clockwise=increase yup?
Because looking at the fuel screw and what it does, it seems to prevent the throttle linkage opening more, so surely screwing it clockwise forces the screw down the thread, stopping the linkage opening as far=less?

[duckruls]

Lean, under-fueling,meh Whatever lmao

Will give the fuel screw another 90deg

Edit-Clockwise=increase yup?
Because looking at the fuel screw and what it does, it seems to prevent the throttle linkage opening more, so surely screwing it clockwise forces the screw down the thread, stopping the linkage opening as far=less?

You are trying to relate a diesel injection pump to how a petrol engine works which does not work I'm afraid, the max fuel screw (Full load adjusting screw) as I understand it adjusts the position of the distributer plunger, its not directly connected to the operation of the throttle.

What you need to do is remove the white ring as this limits the max fuel under full boost, then adjust the max fuel screw (clockwise) until you can see visible smoke in your rear view mirror, then adjust the max fuel screw (anti-clockwise) until the smoke is no longer visible.

Even if you don't remove the white ring use the same process for setting up the max fuel screw, set aside a couple of hours for setting up as it takes a fair amount of tweaking then driving to get the fueling correct.

Althought smoke may not be visible in the rear view mirror it may well be smoking a small amount but it should be an acceptable amount, ideally you want adjust the max fuel screw until it is at a point as close to producing smoke as possible but without any smoke (if you know what I mean), for a road car producing loads of smoke is just a waste of fuel and draws attention to you and your car, loads of smoke to get the last bit of power is ok for a drag strip vehicle but not a road going car in my opinion.

[LongLiveTheNova]

I get you mate, cheers

[duckruls]

I saw what looked like an RHF4 turbo and manifold on ebay from a 1997 Vectra (it had the clamp on exhaust side as DutchNovaDiesel had mentioned).

Feeling a bit wild I put a £5 bid on it and ended up winning it for £2.20 (plus £15 p&p).

It was not a straight swop for me as due to intercooler fitting/pipework I need the turbo outlet pipe pointing upwards, this turbo did not have the usual clamp type fixings for the compressor housing so when it was rotated to point upwards only 2 of the bolt holes aligned so I had to drill and tap 3 new mounting holes.

Its been fitted for a couple of weeks now and has made the engine feel different when driving, I've increased the fuel slightly with no extra smoke compared to when the RHB4 was fitted.

Some of the differences I've noticed are:

When under partial throttle the turbo does not appear to boost as much but once you go to 3/4 or more throttle it boost higher/quicker.

It seems to hold 1.5 bar easier than before, when going from partial to full throttle the RHF4 seems to get to full boost quicker, the rate at which the needle sweeps around to full boost stays the same until the boost controller cuts in, the RHB4 always seems to slow down as it got towards full boost.

A quick (simple) test before swopping them, full throttle from low rpm in 5th gear, RHB4 and RHF4 were both at 1 bar by 2200rpm, the RHB4 took till 3200rpm to get to 1.5 bar were as the RHF4 now gets to 1.5 bar by 3000rpm (maybe a fraction under).

It engine seems to be smoother and more willing to rev higher.

So to summarise I would say under partial throttle it does not seem to be as powerfull/quick to boost but once on full throttle it feels more powerful and boost better, for a total cost of £17.20 I think it was a worthwhile modification

I am going to try water/methanol injection next and once that is done I will get a power run done to see what it is doing (with and without the water/meth injection to see if it is actually doing anything).

[Jack]

That's awesome gen, and a good bargain I reckon! Nice one Duckroll, you are a legend!

A power run sounds ace. I'm looking forward to having an exhaust made for my Cavalier and seeing what it will boost up to.