Options for Compression Ratios 1GR

[iniazy]

Hello guys,

I am working on building a 1GR engine, which I have lying around (had two bad rings from poor supercharging). I would like to build it with reduced compression ratio, to allow me to boost the engine. I am torn between dropping the CR just a little, or significantly.

My initial thought was to drop it to 9:1, but then I started thinking why not go even further and drop it to 8.5:1. What are the side effects of dropping the compression too much? I know less compression means I need more boost, so is there a way to calculate how much boost I need to mke on, say, 8.5:1 CR? My target is around 500 HP.

I'm planning on supercharging it using a Rotrex supercharger.

What are your thoughts and recommendations?

Here's a picture of the engine I'm building:
(too bad I can't upload pictures yet. Need to have ten posts)

This is my second engine build, and first high performance engine build.

 

[darthyota]

just so you know what you will spend on a built motor you can do an ls swap and make 500 na who all day long

 

[Gadget]

10:1 is the best for that application.

G

 

[hottacoX]

I was torn on this as well, to keep things safe(in my mind) with a top HP of 500 as well, I went 9.5:1. I haven't been able to dyno or boost it yet so :dontknow: the overall.

 

[Tunedx]

LS swap Build 1gr if your pockets are deep..

 

[hottacoX]

LS swap Build 1gr if your pockets are deep..

Every time someone asks a performance question you can't get away from those two letters.. Start your swap already :eviltongue:

 

[Tunedx]

Every time someone asks a performance question you can't get away from those two letters.. Start your swap already :eviltongue:

My wife's civic is consuming my life right now.. Hell I don't even have anytime to install my new headers.. Excepting donations now..

 

[iniazy]

LS1 swap will give power, but no reliability. You'll be constantly firefighting problems all the time, and pulling the engine out gazillion times. I've been that route, it ain't fun.

Gadget, I had bad experience with 10:1, getting too much knocking and pinging. I don't know, I feel safer dropping the compression a bit.

Maybe like HottacoX said, at least go to 9.5:1. What boost are you running, HottacoX?

 

[Torspd]

I ran 9.5:1 on my last setup. Was making the numbers below in my Sig, with a VERY safe tune. (Long story which involved JB Weld. )

Not one hint of knock. Had the deck problem not been there, I would have pushed it more.

This new setup I lowered it to 9.0:1. Simply as an additional protection factor. Since I am going for relatively big numbers. Do to the stroker crank, and camshafts, they should make up for any loss of low end due to compression loss.

 

[darthyota]

Every time someone asks a performance question you can't get away from those two letters.. Start your swap already :eviltongue:

its done the x is gone have very gently used ford raptor in its place. needed something a little more practical for work i.e. have the ability to be paid for my vehicle and use it to get around site. wife said if i still want another x in couple of years shed let me pick one up for cheap and let me go to town on it.

 

[iniazy]

I ran 9.5:1 on my last setup. Was making the numbers below in my Sig, with a VERY safe tune. (Long story which involved JB Weld. )

Not one hint of knock. Had the deck problem not been there, I would have pushed it more.

This new setup I lowered it to 9.0:1. Simply as an additional protection factor. Since I am going for relatively big numbers. Do to the stroker crank, and camshafts, they should make up for any loss of low end due to compression loss.

I'm amazed! At only 8.7 PSI you're getting 399 HP on the wheels? That answers my question. I'll go for 9.5 then. I'm not interested in going too high, no where near where you're going.

I'm also considering the Darton sleeves; do you guys think I should sleeve the engine, considering I'm going for no more than 500 HP? Or the standard open-deck cylinders can handle that power? I have to mention that I have to bore my cylinders, if I keep my open deck design, because my cylinder walls are really badly scored. I'll post a pic once I reach ten posts :stupid:

So there's another question: Can the thin cylinder liner take a .5 mm (.020 inch) bore? I think it is only 1 mm thick, so that would take away half of its thickness.

 

[hottacoX]

I hope they do as I went .5 overbore but may never know.... I had my motor rebuilt and have run into a failure before I could boost.... Contemplating walking away as my wallet has taken a beating... although it's not like I don't have options for boost...

Hopefully it gets rebuilt but only time will tell.. Hey while I am on it you have a spare crank? I am in need lol

 

[iniazy]

Sorry I don't. Though I might be able to find some cheap here, but will need to be turned at the machine shop, might be rusty.

I live very far away from you, so probably will cost too much to ship those heavy things half way across the world.

BTW, are you sure your engine failure wasn't because of the .5 over stock bore?

 

[hottacoX]

Haha right on, yeah it would be rather pricey! Toyota wants $7-900 for one here depending where ya go and machining one is about $400...

 

[Torspd]

LC Engineering has been over boring the OEM cylinders .020 over, since before Darton sleeves were even in the works. They would be the ones to contact specifically about the details of that. They also can supply bare short blocks for those that want them.

www.lceperformance.com

They built my engine, which is currently being over built. A lot of good guys there.

 

[iniazy]

Thanks Torspd. I've been in touch with them lately and they assured me that the engine block can take 0.5 mm overbore, but I just wanted to see someone who has done it and running ok.

Now that I reached ten posts, I'll post some pictures of my build and my failures.

I own a Toyota Fortuner, a boxed HiLux, which is like the middle eastern version of the Tacoma. It has a Toyota 1GR V6, and when I attempted the install of the SC, the engine already had 290K KM on the clock (180K Miles), and the engine was already a bit tired. It had some ticking noise that occurred in cold weather on the driver side bank, probably some play in wrist pin or maybe from cam shaft or valves, I will never know.

The engine still seemed to drive ok, though not sure might have been a little down on power. So I attempted the SC install. Ordered a Rotrex kit from Alpine Developments in South Africa (they have the HiLux there), and really wished I had ordered the URD version. I hadn't heared of URD yet then.

Kit arrived, and started installing it on my engine. Here are some pics:

My Fortuner:

The kit after installation:

The kit employed water to air intercooling in a terribly ugly boxy intake manifold which was a nightmare to install and another nightmare to remove:

Intercooler radiator and rotrex oil cooler:

Alpine also included injectors that didn't fit properly, had the wrong o-rings, and leaked fuel into the intake:

Also included was a cheap PerfectPower piggy back system, and they didn't have a workable tune loaded.

And the Rotrex came with a pulley that was too small, produced 0.6 bar of boost (8.7 PSI). So with that boost, and bad tuning (some of that blame comes on me, because I didn't know how to tune it properly at the time), the boost was too much for the 10:1 CR (that's what I think), and the power was too much for my auto transmission, so my first gear started slipping. Eventually, two of my pistons cracked at the compression ring, and the rings also broke. The oil started evapurating and consumption of oil became too high, all of my intake manifold, SC piping, and Rotrex supercharger itself got soaked in oil. I took the supercharger off and continued to drive it like that, while keeping an eye on oil level.

So I drove from Saudi Arabia to the United Arab Emirates with the busted engine, and bought a replacement US-import 1GR from there for a good price. Got that engine in, and started dismantling my unfortunate old engine. Old engine on the engine stand:

Here's how two of the pistons looked like, after the tear down:

The cylinder walls badly scored:

Now here's where my rebuild is starting.

 

[Gadget]

I am wondering what supercharger and pulley size you are running?

I will bet a big part of your problem is not enough charge air cooling.

I have a 2TR Hilux here at URD now. Will have a nice system made for that soon. I really wish I could get a v6 version. Got some leads, there are 25 of them in a secure facility in Northern Virgina I am trying to get access to.

G

 

[iniazy]

I am wondering what supercharger and pulley size you are running?

I will bet a big part of your problem is not enough charge air cooling.

I have a 2TR Hilux here at URD now. Will have a nice system made for that soon. I really wish I could get a v6 version. Got some leads, there are 25 of them in a secure facility in Northern Virgina I am trying to get access to.

G

I was running the same Rotrex supercharger you run on the URD V6 kit, can't remember exact model number but I think something-38 (edit: I think C38-81), with 85 mm pulley. But my crank drive pulley was 175 mm, quite big. That's probably what pushed the boost so high.

That might be so, especially that my intercooler cores were always completely covered with engine oil, probably rendering them completely useless. That's why now I got me an oil separator can from EliteEngineeringUSA.com:

 

[1GRracer]

Could be my screen at work but it looks like the bore is blue. If so then there was a ton of heat in there, cooling the iat's and the oil should be a big priority.

 

[iniazy]

BTW, Gadget, the 4-cylinder HiLux and the V6 have the exact same engine bay and bumper/grill, etc. So an intercooler for the four will perfectly it the six, for example.

And the way I see it, the only difference between your existing kits and the required changes for a HiLux/Fortuner would be the intercooler, since all else is pretty much the same as the US-spec vehicles.