DOHC 4G64 All Motor

[94GST]

I've searched for users who may have done this, but no luck. Not looking for hug horsepower gains, but I wanted to do the following to my future Spyder GS:

7 bolt 4G63T head
Comp 101100s
Custom SMIM with long runners
Custom Unequal length headers
2.5" exhaust including high flow cat and vibrant stealth muffler
450cc injectors
19" wheels 225/40/19 tires
Coil Overs

That's all I can think of right now. I'm just looking for opinions.

 

[LOLVTEC]

well your not going to gain any hp with tires, plus i think those are way way to big. i'm pretty sure your going to rub all over. the same goes with coilovers, no hp gain just for ride stability. as for your custom intake and headers, no one can tell unless you have it flow tested somehow.

 

[WES_393]

None of those mods will give you a noticeable increase in HP without a tune. All it will do is kill torque which is where the 4g64 shines. The 450cc injectors will do nothing but make the engine run rich since the ECU still thinks you have stock sized injectors. And what's with the unequal headers? You definitely want equal back pressure hence why people go through so much trouble for an equal length header.

Save up for a turbo and read up on it in the mean time. Once you have that turbo, a DOHC and bigger injectors will be proper upgrades. With low comp pistons you can have just as much fun (if not more) than the 4g63 guys. Until then, keep it stock and torquey.

 

[94GST]

Haha, I know the wheels/tires and coil overs aren't hp gains, I just included them for opinions on brands. A friend of mine has a Spyder with the same wheel specs and doesn't scrub.

And as far as the 450s, I was going to tune the car for the possibility of another turbo dsm in the future. My GST was fun, but the pistons and valves got into an ugly fight so i'm just trying to relax for a little while. I don't plan going over 10 psi with the hx35 if I decide that path.

So getting a equal length header instead. Any more opinions?

 

[Snot Rocket]

I hope you have done all your research on the head swap. There is a few oil passages that have to be blocked plus the right T belt you have to use.

 

[94GST]

I hope you have done all your research on the head swap. There is a few oil passages that have to be blocked plus the right T belt you have to use.

Yeah, i've done my research on it. My first car I started modding though was my GST, so i'm kinda new to the N/A world.

What body kit is on that 1G in your avatar? Looks nice.

 

[Snot Rocket]

No bod kit just bright ass green paint.

 

[bastarddsm]

I've searched for users who may have done this, but no luck. Not looking for hug horsepower gains, but I wanted to do the following to my future Spyder GS:

7 bolt 4G63T head
Comp 101100s
Custom SMIM with long runners
Custom Unequal length headers
2.5" exhaust including high flow cat and vibrant stealth muffler
450cc injectors
19" wheels 225/40/19 tires
Coil Overs

That's all I can think of right now. I'm just looking for opinions.

Let me lay this down for you. There 3 ways to make more power in an NA engine.
1. More RPM
2. More Displacement
3. Better VE

Better VE is the hardest, and makes the least impact. More displacment is good, but RPM is better.

So if you want to make power you'll want to be able to make power at 8000+ RPM.

Check this out:

BHP = RPM*DISPLACEMENT*BMEP/792000

Use CU IN for displacement, and BMEP is brake mean effective pressure. On a na 4 valve motor it's in the area of 150psi.

Using this, a NA 2.4 that made peak power at 8500 could theoretically make 235hp.

So to get it to make peak power at that high of an rpm, I'd start with building a long rod motor to improve the rod/stroke ratio. Improving that will definatly help high rpm durability. You'll also want some cams in the 280* duration range, and springs to match. I would also use a 1g big port head with one of the newer shorter runner intakes. You'll want pistons in th 10.5-11:1 range, to be pump gas friendly. Additionally you head is going to need to be ported to flow well at .500 lift. I'd suggest a 1.75" diameter equal length header.

I'd also run a flashable 2g ecu and a 2g maf.

If thats a bit extreme, you could scale it back to a 7000rpm 2.4 and possibly make 195hp.
I'd run your existing 2.4, some HKS 272 style cams, a 2g head, and a EVOIII intake manifold. You'll probably want a header with 1.5" diameter primary for this. You could also probably get away with the stock tune on this setup. An AFC to tune the AFR's would maybe be a good idea.

 

[94GST]

Let me lay this down for you. There 3 ways to make more power in an NA engine.
1. More RPM
2. More Displacement
3. Better VE

Better VE is the hardest, and makes the least impact. More displacment is good, but RPM is better.

So if you want to make power you'll want to be able to make power at 8000+ RPM.

Check this out:

BHP = RPM*DISPLACEMENT*BMEP/792000

Use CU IN for displacement, and BMEP is brake mean effective pressure. On a na 4 valve motor it's in the area of 150psi.

Using this, a NA 2.4 that made peak power at 8500 could theoretically make 235hp.

So to get it to make peak power at that high of an rpm, I'd start with building a long rod motor to improve the rod/stroke ratio. Improving that will definatly help high rpm durability. You'll also want some cams in the 280* duration range, and springs to match. I would also use a 1g big port head with one of the newer shorter runner intakes. You'll want pistons in th 10.5-11:1 range, to be pump gas friendly. Additionally you head is going to need to be ported to flow well at .500 lift. I'd suggest a 1.75" diameter equal length header.

I'd also run a flashable 2g ecu and a 2g maf.

If thats a bit extreme, you could scale it back to a 7000rpm 2.4 and possibly make 195hp.
I'd run your existing 2.4, some HKS 272 style cams, a 2g head, and a EVOIII intake manifold. You'll probably want a header with 1.5" diameter primary for this. You could also probably get away with the stock tune on this setup. An AFC to tune the AFR's would maybe be a good idea.

Both those hp numbers sound good, but I was thinking something along the 280 range would be suckish at cruising, since it would be a dd. But thanks for the info, that's what i was looking for.

I was also looking to keep torque.

 

[GST2012GSX]

I will recommend 1g head over the 2g, that's what I'm doing also bigger camshafts.

 

[bradselph]

If you want torque keep the sohc

 

[94GST]

If you want torque keep the sohc

Why would converting to DOHC change anything? Because of the extra camshaft to turn? I'd think that it would hardly matter. Take the KA24E for example, they added another camshaft and gained 5 lb. ft. of torque. Lol, besides, an aftermarket camshaft for a 16v sohc motor would be a pain. Looks like i'll go for raw hp. Do you think the comp 101300s are overkill?

 

[jcart953]

Why would converting to DOHC change anything? Because of the extra camshaft to turn? I'd think that it would hardly matter. Take the KA24E for example, they added another camshaft and gained 5 lb. ft. of torque. Lol, besides, an aftermarket camshaft for a 16v sohc motor would be a pain. Looks like i'll go for raw hp. Do you think the comp 101300s are overkill?

Yes, the cams play a part of it. If i remember correctly keeping SOHC will have a bigger torque curve and make it easier to get equal amounts of HP and torque. Using the the dohc head will change the power curve and make horsepower lead the torque curve. Maybe someone can clarify or add more of a explanation for you.
However, Im interested to see how this project turns out for you. Good luck.

 

[94GST]

Yes, the cams play a part of it. If i remember correctly keeping SOHC will have a bigger torque curve and make it easier to get equal amounts of HP and torque. Using the the dohc head will change the power curve and make horsepower lead the torque curve. Maybe someone can clarify or add more of a explanation for you.
However, Im interested to see how this project turns out for you. Good luck.

Thanks man. What you say makes sense, . I guess i'll give up on the torque because I would like my car to be aesthetically pleasing. But, i'll keep you all informed on the process with descriptions and pictures, as well as dyno charts. Who knows, maybe even a dyno video and playing around at the beach.

 

[91stocker]

Your not going to break 200hp n/a with out a lot of research. The record for the 420a is somewhere around 215whp.

You'd be better off finding an experienced well known engine builder and telling him your plan. Everything has to be just right or your going to be very disappointed.

Or build a honda. They have the recipe laid out for you in detail. Its been done to death over there.

 

[94GST]

Your not going to break 200hp n/a with out a lot of research. The record for the 420a is somewhere around 215whp.

You'd be better off finding an experienced well known engine builder and telling him your plan. Everything has to be just right or your going to be very disappointed.

Or build a honda. They have the recipe laid out for you in detail. Its been done to death over there.

I don't want a Honda. And getting over 200whp would be a plus, but i'll just be experimenting. I'll be satisfied with 150whp in the spyder. As stated earlier, it'll be my dd, not my "I put my foot in this b*tch" car . My second car will sport a HX35, be it another 2g or a 240sx. Maybe both.

 

[91stocker]

I'll be satisfied with 150whp in the spyder.

See i dont think you will be though. 150whp in a 3100lb car and assuming a driver weight of around 200lbs will run an estimated 16.3 in the 1/4. The car is also fwd so that time is assuming a good driver. Its possible it could be a high 16's, 17 flat car. That car would not even fun to drive for a dd.

 

[94GST]

I'll be satisfied with 150whp in the spyder. /QUOTE]

See i dont think you will be though. 150whp in a 3100lb car and assuming a driver weight of around 200lbs will run an estimated 16.3 in the 1/4. The car is also fwd so that time is assuming a good driver. Its possible it could be a high 16's, 17 flat car. That car would not even fun to drive for a dd.

They don't weigh 3100lb like Wiki says. They weigh 3032lbs., slightly more than a gst hatch. And my plans would get me 150whp easily, I don't plan on disclosing my full list until it's done. So far, no one has done this yet. I want to be the first.

 

[T is for TURBO]

They don't weigh 3100lb like Wiki says. They weigh 3032lbs., slightly more than a gst hatch. And my plans would get me 150whp easily, I don't plan on disclosing my full list until it's done. So far, no one has done this yet. I want to be the first.

3100-3032=68lbs. I take craps bigger than that.

From my understanding, SOHC will produce more low end torque as there is less resistance (fewer valves springs, less mass ect.) to fight. Also haveing a smaller total valve opening area, the air velocity should be higher. But once you start getting to the upper RPM range, they start to become restricted. That is where a DOHC really shines, as they can breathe a whole lot better up top.


There are many more variable to the SOHC vs DOHC, such as valve placement, variable valve timing implementation, and sprak plug placement, use of rocker arms, shims, ect.

 

[Archer Fabrications]

Haha, I know the wheels/tires and coil overs aren't hp gains, I just included them for opinions on brands. A friend of mine has a Spyder with the same wheel specs and doesn't scrub.

And as far as the 450s, I was going to tune the car for the possibility of another turbo dsm in the future. My GST was fun, but the pistons and valves got into an ugly fight so i'm just trying to relax for a little while. I don't plan going over 10 psi with the hx35 if I decide that path.

So getting a equal length header instead. Any more opinions?

yeah..... running 10 psi on an hx35 is NOT all motor.... and also way to small psi to have fun with on an HX35....unless your a civic, but even then you will probably blow somehting.

 

[1990AWD]

yeah..... running 10 psi is NOT all motor....

yea, and not reading the thread properly...

He said turbo was an option but is probably going to save it for a future build.

My second car will sport a HX35, be it another 2g or a 240sx. Maybe both.

 

[Archer Fabrications]

yea, and not reading the thread properly...

He said turbo was an option but is probably going to save it for a future build.

well turbo wouldent be an option for an all motor car.... hence the thread title.

i read the thread.
by the way.. do you even have this spyder GS yet?

 

[jcart953]

well turbo wouldent be an option for an all motor car.... hence the thread title.

i read the thread.
by the way.. do you even have this spyder GS yet?

but i think he was just explaining the reason for having his setup a certain way.

 

[94GST]

Goodness, in my initial post, I mentioned the hx35 IF I DECIDE THAT PATH. And I don't have it yet, i'm getting it next year. But, I found a GST Spyder around the same price and I might fall for that one and save the N/A for later. Also, I know 10 psi isn't enough to have fun with it, but it would have to do until I upgrade everything from the stock motor to push the 20 psi that I dream of.

 

[1990AWD]

Goodness, in my initial post, I mentioned the hx35 IF I DECIDE THAT PATH. And I don't have it yet, i'm getting it next year. But, I found a GST Spyder around the same price and I might fall for that one and save the N/A for later. Also, I know 10 psi isn't enough to have fun with it, but it would have to do until I upgrade everything from the stock motor to push the 30+ psi that I dream of.

Fixed