2.8L Astron. TURBO or NA?

This section is for talk about anything to do with everything in the engine bay.
webby
Posts: 1644
Joined: Thu Apr 02, 2009 10:38 am
Location: Parkes, NSW

Re: 2.8L Astron. TURBO or NA?

Post by webby »

I'm an NA junkie so you can guess what my answers gonna be :P
-Josh.
Image
Daily: 7/96 EF Falcon, 4.0 SOHC, BTR95LE, 3.45:1 LSD/Lukey extractors, full 2.5” exhaust, EL intake, Tickford snorkel, 87DA cam, AU injectors, shiftkits.com.au single stage kit. PB 14.93@91mph.
Project: Red '81 Scorpion-http://www.sigma-galant.com/viewtopic.php?f=46&t=11889
User avatar
Rallyant
Posts: 184
Joined: Fri Apr 24, 2009 11:24 pm
Location: Ringwood, Melbourne, (Newport Syd atm) & Seychelles
Contact:

Re: 2.8L Astron. TURBO or NA?

Post by Rallyant »

webby wrote:I'm an NA junkie so you can guess what my answers gonna be :P
Turbo?
webby
Posts: 1644
Joined: Thu Apr 02, 2009 10:38 am
Location: Parkes, NSW

Re: 2.8L Astron. TURBO or NA?

Post by webby »

Yup:D
-Josh.
Image
Daily: 7/96 EF Falcon, 4.0 SOHC, BTR95LE, 3.45:1 LSD/Lukey extractors, full 2.5” exhaust, EL intake, Tickford snorkel, 87DA cam, AU injectors, shiftkits.com.au single stage kit. PB 14.93@91mph.
Project: Red '81 Scorpion-http://www.sigma-galant.com/viewtopic.php?f=46&t=11889
shuggy
Posts: 2269
Joined: Tue Mar 24, 2009 12:35 am
Location: Perth, WA

Re: 2.8L Astron. TURBO or NA?

Post by shuggy »

yeh NA all the way
Billsy
Posts: 662
Joined: Sun Mar 22, 2009 5:43 pm
Location: Adelaide

Re: 2.8L Astron. TURBO or NA?

Post by Billsy »

simple opininions aside, i would go turbo because you will get MUCH more power and torque, and wont have to try and make it rev.
a good sized turbo will be on boost around 2500rpm and could make an easy 300whp without having to rev high. by the stroke of it its not sounding like a hi rpm engine.
so to me the boosted option sounds the go, even a supercharger would be a good choice on it.
Insert witty one liner here -->
User avatar
karl_2ltgc
Posts: 312
Joined: Mon Mar 23, 2009 8:38 pm

Re: 2.8L Astron. TURBO or NA?

Post by karl_2ltgc »

Turbo.

Extra capacity will let you run a bigger turbo with less boost less lag and more power :D
Superscan811
Posts: 1689
Joined: Sun Mar 22, 2009 4:12 pm
Location: Sydney

Re: 2.8L Astron. TURBO or NA?

Post by Superscan811 »

After a long hard think, I've decided to go turbo. Can't think if a better way to "Stress test" my engine design.
I'm planning to lighten the crank a little bit. Something along the lines of this.


Image


Image

After removing the metal from the Big-end, I'll reduce the OD on the counterweights, reduce the throw angle a little, knife edge the OD and trailing edge and round the leading edge

Image

I was also thinking of "Gun Barreling" the Big-Ends, but for a Turbo engine, I don't believe it would last.

Image


Thanks everyone for your input.

Cheers.
Billsy
Posts: 662
Joined: Sun Mar 22, 2009 5:43 pm
Location: Adelaide

Re: 2.8L Astron. TURBO or NA?

Post by Billsy »

i wouldnt remove any metal from where you have marked on the big end, youll likely weaken it dramatically.
nor would i chop that much from the counterweights.
also theres oil galleries in the crank, the "gunbarrelling" as you put it would just bore through them making them useless

with the capacity you have youll want to retain some weight in the engine rotating assembly, it will make it MUCH smoother/easier to drive (especially at low rpm) and realistically will make fugg all difference to the output if you leave it there.
Insert witty one liner here -->
Superscan811
Posts: 1689
Joined: Sun Mar 22, 2009 4:12 pm
Location: Sydney

Re: 2.8L Astron. TURBO or NA?

Post by Superscan811 »

Billsy wrote:i wouldnt remove any metal from where you have marked on the big end, youll likely weaken it dramatically.
I'm going to consult with a few engine builders BEFORE I start doing any major lightning of the crank, although the metal removal on the 2nd picture,
Image
is quite safe, as it serves no real purpose with the reduction in bearing width.
Billsy wrote:also theres oil galleries in the crank, the "gunbarrelling" as you put it would just bore through them making them useless
It was suggested to tap the oil holes before grinding and gun-barreling the big ends. This would allow you to put in a hollow thread bar for the oil passage after.
There is a lot more to it than that but you get the idea.

Cheers.
Billsy
Posts: 662
Joined: Sun Mar 22, 2009 5:43 pm
Location: Adelaide

Re: 2.8L Astron. TURBO or NA?

Post by Billsy »

its nothing i would consider for what your building, considering what little benefit you will gain from it vs the time and effort in doing so.
but none the less, ill be interested to see how it goes once you do it.
Insert witty one liner here -->
User avatar
Rallyant
Posts: 184
Joined: Fri Apr 24, 2009 11:24 pm
Location: Ringwood, Melbourne, (Newport Syd atm) & Seychelles
Contact:

Re: 2.8L Astron. TURBO or NA?

Post by Rallyant »

All looks like a good idea to me.

did you have the crank linished? doesn't look super smooth in the pics.
Superscan811
Posts: 1689
Joined: Sun Mar 22, 2009 4:12 pm
Location: Sydney

Re: 2.8L Astron. TURBO or NA?

Post by Superscan811 »

Rallyant wrote:did you have the crank linished? doesn't look super smooth in the pics.
Not yet. I'm going to get that done then cryo'd but only after I finish lightening it, just in case I put any marks on it.
I wasn't sure if the 6mm narrower big-end diameter, 5mm narrower big-end width and the 3mm offset would interfere with the oil holes,
and if it will hold together after all this work, so this is more or less just a "TEST" crank, just to see if it can be done.
Ideally, a billet crank with twin counter-weights per big-end would be the go, but I can't see that happening in the near future.

BTW: Does anyone know where, in Sydney, I can get a crank tested for flex? The flex values would be good to know for a standard crank and a modified one.


Cheers.
User avatar
cheaterparts
Posts: 660
Joined: Tue Mar 17, 2009 9:06 pm
Location: Cranbourne Vic

Re: 2.8L Astron. TURBO or NA?

Post by cheaterparts »

Superscan811 wrote:
BTW: Does anyone know where, in Sydney, I can get a crank tested for flex? The flex values would be good to know for a standard crank and a modified one.


Cheers.
Scott just rev it till it breaks and back it off a couple of hundred revs from there -lol
cheater
User avatar
81GL
Sigma-Galant Police (Global Mod)
Posts: 912
Joined: Mon Mar 23, 2009 7:27 am
Location: Mildura Sunraysia Vic

Re: 2.8L Astron. TURBO or NA?

Post by 81GL »

cheaterparts wrote:Scott just rev it till it breaks and back it off a couple of hundred revs from there -lol
:lol: LMFAO
Old school Mitsu's, its not a hobby; it's a life style.
Superscan811
Posts: 1689
Joined: Sun Mar 22, 2009 4:12 pm
Location: Sydney

Re: 2.8L Astron. TURBO or NA?

Post by Superscan811 »

Well the 2.8L is officially "ON HOLD".

The 2.8L crank doesn't inspire much confidence in me so I will make a billet crank later (one of the joys of owning your own CNC mill :D ).

I have a spare engine, turbo, pistons, turbo exhaust manifold, W58 gearbox and bellhousing and an ECU, so I may as well build a mild turbo 2.6L engine.

I've already started on the head, "blending" the ports and chamber so as to remove restrictions in the ports and remove possible hot spots and shrouding in the combustion chamber.

I'm not trying to enlarge the ports, just smooth them out and reduce the amount of material around the valve guides. Not always a good idea with a turbo engine because the "excess material" also helps to remove heat from the valves.

This is one of the reasons I will be using Bronze valve guides rather than the standard ones.
I'll also be getting the guides Nickel coated on the inside to help reduce wear.

I'll be running 1mm larger Stainless valves (hence the new valve seats) for my turbo engine, along with bronze valve guides from a Sierra Cosworth.

The standard M7 combustion chamber has a lot of sharp edges that can cause "hot spots" which in turn will cause detonation, ie: DEATH for the pistons.

When I finish "playing", the head will be decked 1mm, to compensate for the material I removed from the combustion chamber blending.

The pictures aren't good but you get the idea.

Image


Image


Image


Image


Cheers.
Post Reply