GTV 116 supercharged NORD

[Midda Samid]

Hi, I am new to this forum thing.. i wish i had known about it 6 years ago when I did the first build..

wondering if there is any information on putting the TS pistons under the NORD head to get the comp ratios down to accept 8-10psi supercharge..?

i hear that the TS rods are shorter, so I guess I have 2 options..
1, I use the short rods with the NORD pistons to get lower comp ratio or,
2, I use TS pistons and NORD rods.. Will the deck height of the piston with the NORD rod be inside the top of the sleeve at TDC?

Does anyone know off hand what the resulting comp ratios will be with either(or both)

Also, reading over Mike(Buzzed)'s twincharge install, he talks about 10548inlet cam with a 10520exh cam to reduce overlap and improve economy/fuel delivery and ultimately HP.. does anyone have any experience with this and is it as simple as putting the cam in, setting the clearances and away you go(i guess it should be the same as any cam install.. perhaps forget this question.. ) Has anyone done this with a forced induction application who can comment?  a second opinion goes a long way.

I am currently running wasted spark ignition, custom plenum, wolf 3Dv4 and it is tuned for the last supercharger install (intercooled SC14).. i found the tune very difficult with lots of fuel and crazy timing to reduce detonation.. I was running 5.5psi.. tired engine but you would think this would help, not hinder.

Any help at all will be appreciated.

[Alan Hopla]

Check out this thread on the alfaBB, it has some discussion about using TS rods or pistons.

http://www.alfabb.com/bb/forums/engine-rebuilding/149621-alfa-75-twinspark-pistons-1984-116-2-0l-giulietta.html

Alan.

[ANG156]

That thread looks familiar.   

My brother started that thread and has done some research on the compression ratio. You may have to pm him on the alfabb if you have further questions. He is running EFI on his Giulietta with multi throttles and sequential ignition, aswell as other custom parts.

[Midda Samid]

Thanks Alan,

looks like the shorter rod is the way to go.. now to source them.. I might hit the calculator and see if i can confirm the compression ratio reduction before i part with my $$ though.

Any idea where i might find the info on the cam question?

Cheers, Dan

[Storm_X]

I have TS pistOns in my nord, haven't started the engine yet .

[Storm_X]

Sorry I would write more but I'm on my I phone at work. Ask me what you want to know I've researched this over the past 3 years.

[Midda Samid]

Thanks StormX,

how was the deck height on the pistons? any protrusion? are you using the Nord rods or TS rods? have you calculated the expected comp ratio?

do the TS pistons and Nord pistons use the same size gudgeon pin(wrist pin)?

Cheers, Dan

[Duk]

Hi, I am new to this forum thing.. i wish i had known about it 6 years ago when I did the first build..

wondering if there is any information on putting the TS pistons under the NORD head to get the comp ratios down to accept 8-10psi supercharge..?

i hear that the TS rods are shorter, so I guess I have 2 options..
1, I use the short rods with the NORD pistons to get lower comp ratio or,
2, I use TS pistons and NORD rods.. Will the deck height of the piston with the NORD rod be inside the top of the sleeve at TDC?

Does anyone know off hand what the resulting comp ratios will be with either(or both)

Also, reading over Mike(Buzzed)'s twincharge install, he talks about 10548inlet cam with a 10520exh cam to reduce overlap and improve economy/fuel delivery and ultimately HP.. does anyone have any experience with this and is it as simple as putting the cam in, setting the clearances and away you go(i guess it should be the same as any cam install.. perhaps forget this question.. ) Has anyone done this with a forced induction application who can comment?  a second opinion goes a long way.

I am currently running wasted spark ignition, custom plenum, wolf 3Dv4 and it is tuned for the last supercharger install (intercooled SC14).. i found the tune very difficult with lots of fuel and crazy timing to reduce detonation.. I was running 5.5psi.. tired engine but you would think this would help, not hinder.

Any help at all will be appreciated.

2 suggestions.

Buy Greg Gordon's book on supercharging and learn as much as you can about water injection!
Greg's book has massive amounts of information about water injection but there is still plenty more you can learn about the subject.
Unfortunately there is also plenty of marketing driven crap out there on the 'net.

Rather than simply dumping compression with questionable modifications like shorter rods, which will leave you with some pretty piss poor squish area, take control of the detonation problem(s).
Obviously a fresh engine will be on the top of your list of 'wants'. And obviously building an engine to suit your forced induction desires is a very good idea and that is always offset with real world funding. But a stupid low compression ratio engine with a cr@p supercharger will be neither powerful, decently drivable or fuel efficient.
A fresh engine that is properly run in, will have very little blow by. This will help keep the knock point as high as possible because blow by gasses heat the inlet charge and any oil mist that travels with it has an octane reducing effect.
IE: It promotes detonation and also causes carbon build up which can get hot enough to cause pre ignition.

For me, if I was building a positive displacement supercharged engine and had to keep using the Toyota supercharger, I would keep compression no lower than 9:1, with a decent intercooler (they are an old, inefficient supercharger that heat the air a lot for the pressure they develop) and water injection to give a tuning advantage at higher boost pressures.
Rather than worrying about camshaft profiles, take advantage of the Alfa's adjustable cam gears to help reduce combustion chamber temperatures. By advancing the exhaust cam a few degrees (have it open a few degrees earlier), the supercharger will help to expel the hot exhaust gasses and help cool the combustion chambers and reduce exhaust gas contamination.
Even if a good rebuild isn't at the top of priorities, a good oil/air separator or a simple externally venting catch can, good water injection and advancing the exhaust cam timing should help a lot with detonation problems. Also make sure that the intercooler's internal surfaces are clean and free from oil deposits.

[Midda Samid]

Thanks Duk,

I am using an Eaton charger this time around, and won't be using water injection.. I figure factory supercharged engines don't use it, there should be no reason I need to at the modest boost pressures I am building for.. I am not interested in big numbers, I had 92kW on the bitumen with the last setup at 5.5psi, and it transformed the car.. my target is about 110-120kW for a strong everyday Alfa.

I am not sure i would refer to a low comp ratio as "stupid", but I take your point on the cr@p charger. For info, the intercooler that is in Buzzed twincharge project was built for my first supercharger project.. so, I had a cr@p charger, and a pretty large tube and fin cooler that was custom built and new, 10548 cams and detonation that had me throwing bucket loads of fuel at it of which it didn't utilise and passed through what I suspect to be the overlap.

I am not sure the shorter rods to reduce compression is a questionable mod either.. If the calc's work out, then infact it will prove to be a very cost effective method for reducing compression in a Nord engine. The calc's will tell.

My understanding of "blow by" in a forced induction system is the charged air and fuel is entering the crankcase past the rings rather than the crankcase venting to the combustion chamber(unless under decell or vacuum/closed throttle). Biggest issue with this is the contamination of the oil with the unburnt fuel reducing it's ability to be oil. I currently have an oil/air separator and am not returning the crankcase vented air to the inlet tract..

I was hoping for a more constructive view on the 10548 v 10520 exhaust cam and will continue on my quest.. What Buzzed had to say about it made pretty good sense to me.. and considering the difficulty I had with the amount of hydrocarbons in the waste gas, is worth a try. I have a set of 10520's so will give it a go.. it's only time afterall.. What you say about the 10548 and advancing the exhaust cam to further add to the overlap I am not sure will help, but again, is worth trying.. Thanks for the advice..
cheers, Dan

[Duk]

I am not sure i would refer to a low comp ratio as "stupid", but I take your point on the cr@p charger. For info, the intercooler that is in Buzzed twincharge project was built for my first supercharger project.. so, I had a cr@p charger, and a pretty large tube and fin cooler that was custom built and new, 10548 cams and detonation that had me throwing bucket loads of fuel at it of which it didn't utilise and passed through what I suspect to be the overlap.

'Stupid low' compression would be less than 8.5:1 when you have all of the tuning potential of a programmable computer and decent forced induction.
I wasn't aware that you were using an Eaton SC and they are definitely a MUCH better supercharger than the olde Toyota unit. They are still flat out around a 1.9-2.0:1 pressure ratio, though. I hope you are using an M62 rather than an M90.

I am not sure the shorter rods to reduce compression is a questionable mod either.. If the calc's work out, then infact it will prove to be a very cost effective method for reducing compression in a Nord engine. The calc's will tell.

Compression numbers are like quoting something like a weight distribution percentage, it tells some information but leaves out a lot of crucial stuff in the process. It's potentially very misleading information about what's going on/what the potential is.
The squish characteristics will effect how much stagnant air and fuel mixture exists around the periphery of the combustion chamber. Stagnant air/fuel mixture can cause detonation and incomplete combustion.

My understanding of "blow by" in a forced induction system is the charged air and fuel is entering the crankcase past the rings rather than the crankcase venting to the combustion chamber(unless under decell or vacuum/closed throttle). Biggest issue with this is the contamination of the oil with the unburnt fuel reducing it's ability to be oil. I currently have an oil/air separator and am not returning the crankcase vented air to the inlet tract..

Don't worry to much about gasses getting past the rings during the compression stroke, that pressure differential has nothing on combustion pressure. 130-180 ish psi vs 1000+psi. Blow by is therefor combustion gasses that get past the rings.

I was hoping for a more constructive view on the 10548 v 10520 exhaust cam and will continue on my quest.. What Buzzed had to say about it made pretty good sense to me.. and considering the difficulty I had with the amount of hydrocarbons in the waste gas, is worth a try. I have a set of 10520's so will give it a go.. it's only time afterall.. What you say about the 10548 and advancing the exhaust cam to further add to the overlap I am not sure will help, but again, is worth trying.. Thanks for the advice..

Buzzed is certainly a clever bloke and his advice should definitely be taken on board.
Greg mentions in his book about the advantages of the correct amount of valve overlap in supercharged engines. Those advantages are not available to turbocharged engines because of the pressure build up caused by the turbine housing.
Twincharged engines (like Buzzed's engine) can be thought of as a supercharged engine in this instance as the compound pressure ratio caused by the 2 compressors will give a higher boost pressure than exhaust manifold/pre turbine housing pressure.
If you have the cams to play with, that's great and maybe worth a play. I wouldn't chase after them for the sake of a force fed engine myself.

[shane wescott]

Gregs Book on supercharging is full of everything you needed to know but forgot to ask :-)

[Storm_X]

Thanks StormX,

how was the deck height on the pistons? any protrusion? are you using the Nord rods or TS rods? have you calculated the expected comp ratio?

do the TS pistons and Nord pistons use the same size gudgeon pin(wrist pin)?

Cheers, Dan

There is a slight protrusion that i was worried about, but it will be fine.
Im using the TS pistons with nord rods.
Dont know the comp ration at all.


I was going to rebuild the motor with the TS rods and nord pistons,but i bought some dellorto carbs,turbo manifold and a dizzy  to retard on boost. While speeking to the guy he said it was on his Alfetta in a 2.0 nord , standard rebuilt motor with 10548 cams and TS pistons running 150rwkw at 15PSI so then i decided to just use the Pistons and not the rods.
He was running a standard vlturbo turbo or similar and claimed it was on boost around 3k.
So i have rebuilt my motor exactly the same but now i am going to run fuel injection, e85 fuel and water to air intercooler.

[Midda Samid]

From what I have read the comp ratio with Nord rods and TS pistons is down in the low 7's.. pretty low.. I expect you will be pushing large quantities of air into it for such a low compression..? I guess the protrusion will be covered by the head gasket thickness?

I have calculated around 8.4:1 for the nord pistons on TS rods and bought a set last week based on this... on the hunt now for an engine to put them in..

I have stalled with my install due to the auto tensioner that I am using on the supercharger belt run.. I had adapted a BA falcon plastic wheel spring tensioner to the aircon bracket, but the load on the belt is ridiculous.. I am chatting with the tensioner manufacturer to find an alternative.. I might have had a breakthrough today with a lower spring rated Jeep 4.0L belt tensioner.. Will source one and get the mounting block milled down to accept it's different offset.

My dream is to have a setup that is shelf stock for all used items.. I am planning a Jaguar XJR airbox and air filter modified to fit the small gap between the top of the splash guard and underside of the bonnet in the space between the brake booster and the edge of the engine bay.. I will feed cold air to it via ducting and maybe turbodelta style bonnet vents to try to keep the car looking it's age. Belt tensioner looks to be a Dayco branded Jeep unit now and the rest is not expected to wear out.. Charger is C230 Mercedes (Eaton M45) and belt is a 5PK1295.. I will have a 12inch push fan and 10 inch pull fan with the 550x145x65mm intercooler mounted forward of the push fan. The supercharger bracket will have inlet and outlet incorporated into it and the pipe runs to the intercooler will be minimal and 2.5 inch. I have to up to 3inch at the throttle body as I am using the Ford Explorer unit.. Custom alum plenum, supercharged commodore v6 injectors and Wolf 3d v4 computer with wasted spark coilpacks.

Apart from the TS rods, the engine will be stock with cams as discussed being the 10548 inlet and 10520 exh. I'm looking for 10psi and 120kW at the wheels.. Last build was 5.5psi and 92kW ATW on a stock smokey motor with 10548's.. I'm remaining hopeful.. The only thing I haven't calc'd is the drive ratio and until I run it, I won't be changing anything.. The charger pulley is about 68mm and the drive pulley is 125mm.. So I have a little room to move. The charger is efficient up to about 14000rpm, so I can increase the drive pulley a fair bit since the engine max revs will remain around 5200-5500rpm and realistically rarely see it since it will be a street car and I am too old to show off...

Anyway, thanks for the interest.. if anyone can think of tips or advce, let me know.. I'll post some pics when I get the belt issue sorted and soon after that it will be running on the old engine.

Has anyone adapted a smaller alternator onto the Alfetta GTv that they can give me some advice on? I have a close proximity with the tension side of the belt with the standard 65A Bosch unit and would like a smaller diametre alternator to be able to rock the whole system further away from the engine and down toward the oil flter on the standard mount.. Buzzed has said that some people use Barina?? alternators.. from what I have read they are about 80-100A and the pics show them to be pretty small.. if anyone has done it, does the pulley swap over and align on the standard mounting?

Cheers

[MD]

The Barina alternator I am using is rated at 40 amps which is too small for a street car.

[Midda Samid]

OK, so finished article.. don't mind the aircleaner, it's very temporary.. as is the engine.. i haven't built the low comp engine yet.

First run has a net boost of 2.5psi with the charger stock pulley at somewhere around 70mm and the custom drive pulley at 125mm.. Drive ratio is 1.78:1 or thereabouts. Admittedly i was calc'ing expected boost of 6-7psi based on incorrect charger displacement data.. I thought I was turning 0.96L/rev but my latest data says it's 0.74L/rev.. vastly different.. never mind, i was always going to be increasing the drive ratio to get my numbers. to be honest, i am surprised the difference even 2.5psi makes to the pulling power of the alfetta.

Struggling to post a photo though.. I am a novice at this.. anyone have any ideas? All the "insert image" button gets me is below..