Turbo psi and rpm

[Vector]

does anyone know where i can get a chart that shows what boost is created at a certain rpm like 9psi? = 100,000rpm or somthing like that for a small turbo from a geo or a volvo.

i did some searching mainly under google, altavista and some time here looking and unless i overlooked somthing i couldnt find any reference just only on how they work.

thanks for your time.

[gfrg88]

try looking them up at HMT

[ZackieDarko]

HMT = www.homemadeturbo.com if you didn't know Vector

[smufguy]

you have to check the flow charts for the compressor ur looking at. That tells you how much air it can flow for a given speed of the turbo. You cant really pinpoint how much boost you can push.

As long as your top end of the motor, matches up with the center of the chart, which is the most efficient area of the turbo, you can be guranteed that the turbo will not surge on you and you will have a satisfied powerband.

[Vector]

well, basically i got my toy today, its a IHI RHB5 Turbo from a friend that came out of a ford probe.

well here goes, i'm only using half and the other side i've started to fab up a drive system that could go 10-15 to 1 ratio to the compressor housing, i dont suspect i will have to many problems with the fuel atomizing and going through the turbo(maybe even going through the turbo will help it more?

from what i've been reading aparently these turbos are not the greatest, but favoured due to there size(easier to install as a whole unit), but it was free and right now i'm just experimenting. i plan on working on this all weekend, shouldnt take to long to put together since i have everything to do it now.

according to bryan (friend/mechanic) who is very familiar with boosting, says that even the kehlin carb will do the job within reason if properly tuned, and maybe even last quite some time if i dont ratbag the car everyday .

mainly i'm just doing this for learning purposes, and if it doesnt work, i have an extra engine lol!
mine as it sits has 311,000k's on it, this is gonna be fun!

[smufguy]

Dont have a clue what the ratio ur talking about. What is it in relation to?

[A20A1]

...i dont suspect i will have to many problems with the fuel atomizing and going through the turbo(maybe even going through the turbo will help it more? ...

...according to bryan (friend/mechanic) who is very familiar with boosting, says that even the kehlin carb will do the job within reason if properly tuned, and maybe even last quite some time if i dont ratbag the car everyday ...

So wiat you're doing a draw thru turbo system?

Have you upgraded the fuel pump?

As for the Keihin working, yes any carb can work, but it wont be easy tunning the keihin, the 3rd gen accord keihin doesn't allow for the main jets to come out easily and the idle jet, what I suspect is the idle jet, even if it is changable what do you change it with. Basicly you'll have to drill them, or drill them out completely and tap in holes for new jets. I was trying to fit weber jets in there at one time. But drilling, there is no going back, you drill too much then thats that.

Good luck trying to unscrew the powervalve as well, I ket trying and stripped it every time, even with the correct sized socket... really dissapointed me.

[Vector]

i'm gonna start with the kehlin, then move up from there as i see fit. Yes this is a draw through system, i'm even working on a fuel drain system for the turbo so it doesnt puddle up to much.

[A20A1]

Did you rebuild your turbo with a carbon seal? most draw thru systems require it because of the vacuum created by the throttle plates being closed sucks out the oil from the turbo... and oil in the combustion chamber supposedly bumps the compression ratio or decreases the octane rating of the gas, one of those... anyways you run the risk of detonation along side turbo damage from loss of lubricant.

The carb tends to run a hotter plug then the efi stock, with turbo I can see you dropping at the least one step colder, to an efi plug.

[Vector]

Did you rebuild your turbo with a carbon seal? most draw thru systems require it because of the vacuum created by the throttle plates being closed sucks out the oil from the turbo... and oil in the combustion chamber supposedly bumps the compression ratio or decreases the octane rating of the gas, one of those... anyways you run the risk of detonation along side turbo damage from loss of lubricant.

The carb tends to run a hotter plug then the efi stock, with turbo I can see you dropping at the least one step colder, to an efi plug.

not yet and i probably wont this time around as i'm going to put in a 1/2" air bleed in between the carb and the turbo housing for idle and cruising so that the vacuum isnt to high, might have to rig somthing for more fuel as well as it will lean out if i do this, but this is all a learning exp for me an anyone else that wants to tag along lol

[A20A1]

Yeah a simple air bleed would not help because it would lean out, and adding fuel+airbleed would be like opening the throttle again.

Maybe some way to soft land the throttle so vacuum doesn't spike.

I don't think drilling a hole in the throttle plate would be an option you'd might end up off the idle circuit perhaps and may have a runaway idle situation.

Or possibly but a exhaust break on the exhaust end... though this will hurt performance.

[Vector]

Yeah a simple air bleed would not help because it would lean out, and adding fuel+airbleed would be like opening the throttle again.

Maybe some way to soft land the throttle so vacuum doesn't spike.

I don't think drilling a hole in the throttle plate would be an option you'd might end up off the idle circuit perhaps and may have a runaway idle situation.

Or possibly but a exhaust break on the exhaust end... though this will hurt performance.

hehe actually, i'm not going all out turbo, but actually powered by the engine itself via chain mechanism off the engine. i will most likely mod/build it as a bolt on then test it to make sure it will not fly apart @ 6k rpm. i'm sure with the proper tentioning setup a chain should be able to handle it. then as for the ratio's i mentioned earlier go 10-12:1

no waste gate or bov if i can help it.

for every 1 rotation of the engine, the turbo will make 12

so if i'm idling(1k mines set for), the turbo will be at around 12k rpm
at 6k rpm the turbo will be at around 72k rpm

i'm also looking into an adjustable centrifugal clutch with tensioner.

oh yea and being as small as it is, i'm sure it will not rob that much power from the engine which is a good thing.

[A20A1]

Oh... so you making like those centrifugal blowers/Supercharger, thats cool.

[Vector]

thats the plan, dont know if the engine will like it, take it, probably fly apart.
i have a backup so i'm not so worried, if it only lasts me 2 auto-x sessions i've laughing lol

[Swap_File]

These two sites are really handy for doing calculations for turbos and superchargers:

http://not2fast.wryday.com/turbo/maps/

http://www.turbofast.com.au/javacalc.html

[AccordEpicenter]

yeah i wouldnt worry much about the engine taking the boost if its in good shape. I pounded mine with 13lbs all the time and 17lb peaks and when it actually went it wasnt really a boost related problem, the pistons and rods looked great, so did the stock headgasket. The oil pump and bearings gave up ghost

[Accordtheory]

A chain driven centrifugal compressor with a gearset you just machined in what, your back yard?

Be sure to post pics..