Turbocharging a non-turbo motor

[Greg]

Out of curiousity and just for something to discuss...

If you were to take a motor (4 cyl) that was not intended to be turbocharged, could you leave the compression somewhat stock (about 8.5 or 9 to 1) and keep the boost levels low?

The engine in question would recieve aftermarket pistions (forged or hypereutectic) to replace cast, and also a camshaft that was turbo-friendly (minimal to no overlap.)

I'm wondering if you could build a motor that had enough torque on the low-end, without boost kicking in, to be usable. Then, when you got into the throttle you had boost. I'd think you would have to limit boost quite a bit, since the compression ratio would already be high, for a motor w/ boost.

Discuss...

 

[bobdog]

If you are replacing pistons you should be able to lower compression.

 

[Greg]

If you are replacing pistons you should be able to lower compression.

Yes but I don't want to drop the compression...

 

[ronnyg801]

Why wouldnt you want to lower the comporession? With the right set up you could have boost at lower rpm's. If there is an option for super-charger I would look there first. But it would be more "trick" to have a turbo or less common for sure not that super-chargers are all that common.

 

[Greg]

For bottom end torque... I am looking for a setup that didn't rely on boost at lower RPM's and puts out about 10-12 pounds of boost at the most at a higher RPM.

Supercharger eh, turbos are cooler. I think turbos work more... efficently? Superchargers are usually something that you have to buy in a kit, which = lots of $$$$. I think you could fab up a decent turbo system for alot less.

 

[tiny2085]

Turbo's run off of your exhaust gasses right. So if you were to only route two cylinders through the trubo you would have little or no boost on the low end of the curve, but at higher rpm the flow would increase enough to show an improvement in performance. Also, blow off valves are able to be adjusted, so what if you were to set the valve low so it would not build boost, but then let the valve run the boost up when you wanted to do so.

 

[N-Smooth]

So if you were to only route two cylinders through the trubo you would have little or no boost on the low end of the curve, but at higher rpm the flow would increase enough to show an improvement in performance.

would that work to run off of 2 cylinders? seems like it would cause problems to have different exhaust compression on different cylinders.
i am new to the whole turbo thing (with my truck) so i don't know much, usually it makes sense though, but this idea seems odd.

 

[Greg]

Turbo's run off of your exhaust gasses right. So if you were to only route two cylinders through the trubo you would have little or no boost on the low end of the curve, but at higher rpm the flow would increase enough to show an improvement in performance. Also, blow off valves are able to be adjusted, so what if you were to set the valve low so it would not build boost, but then let the valve run the boost up when you wanted to do so.

2 cyl... Mabey I shouldn't be talking about boost on a 4x forum. Anyone know a good Ricer forum?

Yeah, the BOV would be set low.

 

[Shawn]

2 cyl... Mabey I shouldn't be talking about boost on a 4x forum. Anyone know a good Ricer forum?

Yeah, the BOV would be set low.

http://www.i-club.com/

 

[spencurai]

You have serious problems with tuning turbo motors. Unless you have someone to reprogram your ECU and get your injectors right, you are not going to get far. IF your Ecu has the wrong map then it is goin to constantly fight the increased volume provided by a turbo.

Putting a turbo on a motor that is carburated....is a pain in the ass also...but that is another story.....

 

[Greg]

It would be EFI... I'm talking a 22RE, FYI. Not a 22RET, but using the RET exhaust manifold and a turbo other than the Toyota RET turbo. I understand that they are pretty poorly designed units.

I was thinking larger injectors would handle the fueling, but I'm pretty boost-clueless. Like most things, I know enough to talk my way into trouble.

 

[Greg]

http://www.i-club.com/

Thanks....

 

[BBowski82]

It would be EFI... I'm talking a 22RE, FYI. Not a 22RET, but using the RET exhaust manifold and a turbo other than the Toyota RET turbo. I understand that they are pretty poorly designed units.

I was thinking larger injectors would handle the fueling, but I'm pretty boost-clueless. Like most things, I know enough to talk my way into trouble.

Is the 22RE a mass-air motor?? Mass-air motors run really well with turbos...you run into problems with speed density based FI (MAP, TPS, CTS)...As far as bottom end torque--GEARS?

 

[Greg]

Is the 22RE a mass-air motor?? Mass-air motors run really well with turbos...you run into problems with speed density based FI (MAP, TPS, CTS)...As far as bottom end torque--GEARS?

Yep, Mass Air... good to know.

What I'm thinking is trying to build a 22RE that has enough power to spin tires offroad for long, steep climbs. Also something that would add just a little more get up & go on the street. The vehicle would be geared for the tire size & probably have plenty of gear reduction.

I like the simplicity & reliability of the 22RE, but it would be nice to have a little more power.

 

[BBowski82]

Yep, Mass Air... good to know.

What I'm thinking is trying to build a 22RE that has enough power to spin tires offroad for long, steep climbs. Also something that would add just a little more get up & go on the street. The vehicle would be geared for the tire size & probably have plenty of gear reduction.

I like the simplicity & reliability of the 22RE, but it would be nice to have a little more power.

I've toyed with the same idea....I was even thinking of running like a cutout valve from, or to, the turbo so that I could shut it down in slower more technical areas.

Turbo's are sweet, but I am not sure how well they would work for our sport. I have 2 buddies with turbo'd sand rails and they are torquey and fly when wound up......

 

[SnwMnkys]

For one Blow off valves dont regulate the amount of boost you build, thats the Wastegates job. Youd never want to run a turbo off of half your exhaust, that would be a tuning nightmare if you could even get it to run propery. I would just put in low compression Forged pistons and then get a turbo properly sized for what you want. You can have a turbo build boost right off of idle. Most people buy them bigger for more HP up top.

 

[SnwMnkys]

I've toyed with the same idea....I was even thinking of running like a cutout valve from, or to, the turbo so that I could shut it down in slower more technical areas.

Turbo's are sweet, but I am not sure how well they would work for our sport. I have 2 buddies with turbo'd sand rails and they are torquey and fly when wound up......

Assuming you could even get a bypass routed to keep exhaust gasses from getting into your turbo to spin it, how would you the air to your motor if theres a turbocharger in the way thats no longer spinning? Just because Mad Max could do it in a movie doesnt mean that Turbochargers and Supercharges can be shut off and turned back on with a flip of a switch.

 

[BBowski82]

Assuming you could even get a bypass routed to keep exhaust gasses from getting into your turbo to spin it, how would you the air to your motor if theres a turbocharger in the way thats no longer spinning? Just because Mad Max could do it in a movie doesnt mean that Turbochargers and Supercharges can be shut off and turned back on with a flip of a switch.

Dude.....I think I have thought it out a little further than that I am in Engineering for Ford MoCo...You would run 2 turnouts if need be...

 

[Tacoma]

I am in Engineering for Ford MoCo...

Well there ya go, it'll never work! hehehehe

Out of curiosity, how difficult is it to tune the turbo's rpms if you're running it to boost off-idle... by that I mean, how close does one come to exceeding the max rpm of the turbo itself, if it's producing boost off-idle, all the way up to redline? Does that limit the top end to a certain rpm or am I not thinking clearly here?

 

[BBowski82]

Well there ya go, it'll never work! hehehehe

Very funny....Ford's product quality is actually improving leaps and bounds...

Out of curiosity, how difficult is it to tune the turbo's rpms if you're running it to boost off-idle... by that I mean, how close does one come to exceeding the max rpm of the turbo itself, if it's producing boost off-idle, all the way up to redline? Does that limit the top end to a certain rpm or am I not thinking clearly here?

I understand what you are saying, and yes you are correct. Running too small of a turbo on an engine is like sucking the air for a big block through a straw....this is why guys run dual turbo setups. For instance, Ford's new 4.5L V6 deisel uses a dual turbo setup with a smaller turbo spooling a larger turbo. Old heavy duties used turbos to feed superchargers....