so I'm considering building a motor

[NiftySVX]

I've been toying with the idea of building a motor for my SVX. I don't want to spend all that much on parts for it, and I think I'd stay stock with the block as I don't need to make any more than 300 crank and even that seems to be a lofty goal with this motor. There is so much info on this subject, but I'm hoping one of the engine guys will give me an idea of what I'm looking at. I have a motor available to me for $100 that has a broken head from an accident way back in 2000, it'sa 94 and has 63,000 miles. It needs a RH head, it's broken.

What I want to know is, can you get in hp/torque just from headwork? If I wanted to stay stock on the valve size, and I just did cams, and a polish, what kind of hp gain could I get? Would it be worth it?

[oab_au]

Originally Posted by NiftySVX

I've been toying with the idea of building a motor for my SVX. I don't want to spend all that much on parts for it, and I think I'd stay stock with the block as I don't need to make any more than 300 crank and even that seems to be a lofty goal with this motor. There is so much info on this subject, but I'm hoping one of the engine guys will give me an idea of what I'm looking at. I have a motor available to me for $100 that has a broken head from an accident way back in 2000, it'sa 94 and has 63,000 miles. It needs a RH head, it's broken.

What I want to know is, can you get in hp/torque just from headwork? If I wanted to stay stock on the valve size, and I just did cams, and a polish, what kind of hp gain could I get? Would it be worth it?

The eternal question. As the engine achieves 106% volumetric efficiency now there is not much that you can do, to increase the amount of air in the cylinder, hence the torque that the engine has now. Sure you can spend time matching the ports to the injector stacks, manifold, removing any imperfections, but you will only get satisfaction of a job well done, no noticeable difference.

To get the 300HP you have to get the engine to produce the same 228ft lbs of torque at 6200, then the engine would give 300 @ 6900. There in lays the problem moving the torque peak from 4800 to 6200. The inlet and exhaust resonate, and valve duration are all centered on the 4800 point.

You would have to do a lot of surgery on the inlet manifold tracts, to get it to the new resonate point the exhaust is easier. So you are left with the only option of using a small amount of duration and lift increase to stretch the torque curve further up the rev range.

The inlet cam is the easiest to do, and the 247* 8mm lift does do that without affecting the low speed torque. You can get a bit more using 257* 8.75 lift cams both on the inlet and exhaust, but the low end will suffer. So if you are going to use an Auto with the 3.5 ratio, you will still need the low end of the torque curve. If you go to a lower ratio or a manual, you can get around using the low end.

Harvey.

[SoCal LS-L]

Bah, why do anything Harvey said, when you can just install one of THESE bad boys Ultra supercharging turbo HP gainer module!!!

Install and enjoy

[FriendlyTurkey]

To do cams properly, you need longer valves, springs with more compression travel before binding, and solid lifters. If you do this, along with some strong cams, you can make lots of power on a stoke short block(crank,rods,pistons). EFI Logic's EG33 impreza was making around ~285 awhp hp with a factory short block with the above mods.

Justin

Originally Posted by NiftySVX

I've been toying with the idea of building a motor for my SVX. I don't want to spend all that much on parts for it, and I think I'd stay stock with the block as I don't need to make any more than 300 crank and even that seems to be a lofty goal with this motor. There is so much info on this subject, but I'm hoping one of the engine guys will give me an idea of what I'm looking at. I have a motor available to me for $100 that has a broken head from an accident way back in 2000, it'sa 94 and has 63,000 miles. It needs a RH head, it's broken.

What I want to know is, can you get in hp/torque just from headwork? If I wanted to stay stock on the valve size, and I just did cams, and a polish, what kind of hp gain could I get? Would it be worth it?

[Alex-svx]

I have also woundring about this stuff. I have been on ECU tune website.
Are these engine parts give HP or must you have some other. I have try also to find N/A tune parts, But i have only fine these. Are the some other website that have tuning stuff for the Svx

And what must will you give for get around 280-300Hp?

[svxistentialist]

This is my take on it, accept or reject as you see fit.

Doing cams and valve work on this engine must surely be for the challenge challenged among us. It's an awful lot of expensive head work for F all return.

Now I would see sense in leaving the cams and valves alone and going for a bigger swept volume using a rebore and larger pistons to 3.5 or 3.7 litres, I haven't done the numbers. { but if 3.3 ~ 225hp, then 3.5 ~ 240hp and 3.7 ~ 250hp without tuning.}

Then, while you were buying your bigger pistons, you go for lower compression, something like 9.5 to one or so.

Next you add either a turbocharger or a supercharger and compress the charge 4 lbs, maybe 6 or 7 lbs, a half atmosphere sounds about right. Some European cars like Saab and Citroen got this factory upgrade which worked very well on real roads, LPT they called it, Light Pressure Turbocharging.

It should be easy and inexpensive to add a small fast spooling turbo, no intercooler, just add water injection or water/meths mix injection.

It will at this stage need a new exhaust because the standard system will not breathe fast enough [have low enough back pressure] for the output.

Probably because you are a technician and you have a broken head on one of the blocks you actually want to do the headwork. And we can encourage you to do it and spend all that time gaining a few geegees up in the stratospheric end of the rev range where it is only really useful for track work.

And because I am not a technician, but merely a driver, I would want my engine to give me a kick in the back, not a kick in the wallet.

Horses for courses, eh?

Joe

[Sov13t]

Very well said Joe!

[RallyBob]

Originally Posted by FriendlyTurkey

To do cams properly, you need longer valves, springs with more compression travel before binding, and solid lifters. If you do this, along with some strong cams, you can make lots of power on a stoke short block(crank,rods,pistons). EFI Logic's EG33 impreza was making around ~285 awhp hp with a factory short block with the above mods.

Justin

After some tuning it was making 292 awhp. With stock cams and stock heads it made 221 awhp. So a 71 whp gain on the same dyno, same car, same shortblock. Granted, that was with aggressive cams and some pricey machine work, but the porting and valve sizes are very modest. About half that number (30-35 whp) should be attainable with the standard valvetrain, very mild porting (mostly on the exhaust ports) and reground cams instead of welded/ground cams.

The power improvements from the new 3.5 litre shortblock were not as radical (+26 whp), but the torque also got proportionately better, and it picked up across the entire powerband as well (including low rpm). Engine flexibility was improved too.

It's running 11.95:1 compression on 93 octane pump fuel with 38 degrees of total timing.

[Gamesy]

is it even possible to bore to 3.7L? and even then the engine would be more fragile wouldnt it?

[SilverSpear]

Yes it is possible. Check YouTube

[svxistentialist]

Originally Posted by Sov13t

Very well said Joe!

Thanks Soviet.

I'm not into raining on anybody's parade or dampening anyone's aspirations, but to me valve work and camshaft work and head work is primarily about delivering horsepower higher up the rev range, and mostly useful for racing, not road cars.

Add to that the SVX is a heavy car with a sluggish gearbox and the obvious upgrade it needs is more torque low down in the rev range to get its fat butt rolling. Bigger brakes are nice too.

[FriendlyTurkey]

Originally Posted by SilverSpear

Yes it is possible. Check YouTube

To get a 3.7L engine you'd need to go to atleast a 102mm bore if you didn't change the stroke. The darton sleeves are rated at 100mm max bore for the eg33. You'd have to check with darton to see if they are safe to bore beyond that for a NA application. You could offset grind the crank to Honda B series crank journals. That would give you about a 78.5mm stroke. You have to be careful doing this as it will make the crank stiffness decrease due to less overlap between the crank journals.

100 x 75= 3.534L
102 X 75 = 3.677L
100 x 78.5 = 3.699L

[NiftySVX]

Ya'll talked me out of it. Haha. I would consider boring and sleeving but that is a PITA on an open deck alloy block. I think my new transmission is about the best performance mod you can make to this car without using forced induction.

[FriendlyTurkey]

You can still overbore the motor to 100mm with stock sleeves. That will get you all the displacement you'd need. Do some nice cams, and exhaust and you are good!

[SoCal LS-L]

Originally Posted by SilverSpear

Yes it is possible. Check YouTube

Whoa, that guy is in Costa Mesa too apparently. His shop is about 4 blocks away from my house.