Turbo Computations Help?

Hey all,

I'm trying to decide on how I want to build up the 6. I'm pretty much positive I'd like to turbo it. I found a site (linked to on here) that helps you do the computations to decide on the size and stuff from a turbo. The values entered are basically put in by the member that linked it before. Could somebody possibly look them over and see if they're good for a fairly stock 200?

Here it is:
http://i.imgur.com/oNTZI1nl.jpg

A couple other questions instead of starting a new thread:

Would 15psi be asking too much of the stock bottom end? If so, what psi would be better? Eventually a 2bbl with a custom intake mounted on a late model log is in the plan. I'm asking because that's what the other member entered in as their boost. I was originally thinking like 8 or 10 psi.

Is 12:1 a resonable fuel ratio? This was also entered by the other member.

Im not very familiar with the 200 but nothing seems glaringly wrong about those input numbers. I'd say 15psi is pushing your luck. The crank and rods can likely take it but the pistons will be well beyond there safety factor. Also, avoiding knock without a very high octane fuel is gonna get pretty hard at that psi. That being said, I plan on pushing 20psi in my 300 but I wont be mad if it breaks, I'm more interested in what it will handle not what it can reliably handle.

What fuel do you plan on running, 93 octane at least I hope. Did you use those inputs to search for a turbo? I used that very same calculator when searching for a turbo for my 300, dont regard it as a 100% bet your bottom dollar kind of thing, its largely an estimate. If you are in the map at all then the turbo will likely work. Whether it spools where you want it may be a different story.

yeah i was screwing around with that turbo calc the other day and i'm not really sure how it works.. i.e. what math they are using on the backend. It seems kinda weird compared to how i would go about sizing a turbo. I think its more just so you can have an easy tool to plot the curve on a turbo map, once you know all the numbers. There was another one i'd used in the past, i think it was all in german, that was really good and practical, but i was looking the other day and couldn't find it.

as for 15 psi on a stock bottom end, perhaps... the pressure comes from turbo flow x head flow resistance- think ohm's law v=I*R - so on a restrictive head you can see higher pressures at the carb before your cylinder pressures get into the detonation zone... but 15 psi is pretty huge for a carb'd engine. I saw a good graph the other day, should have saved it... hmm.. basically unless you want to run race gas, you're limited to about 10 psi max on a 8-9:1 CR engine running 91 octane.

depending on your stock CR and fuel you're detonation limited, but that also depends on timing, swirl, quench, and other factors. you can pull timing like crazy and keep it from detonating, but your power will drop more than the gain from running higher boost.

I'm not sure why everyone starts a turbo discussion with 'can i run xx psi' aside from the notion that xx psi= yy horspower, the boost pressure ends up being the very last thing that you determine after you've built the engine.

Best advice i can give someone doing their first turbo build is to copy what someone else has done, luckily 'does10s' 'lincs200' and 'firstfox' have all done really good writeups on their turbo installs ranging from mild to wild. Just pick whatever one fits your skills and budget, and try to copy as close as you can.

if you're looking for a turbo that is budget friendly, the TD04HL-15G from the Volvo 850/V70.. and others.. is a nice little unit that should be sized well for what you're doing. Built in wastegate and diverter valve, pretty cool. I'm working with one right now on my 300.

totally agree with the "Follow the leader" approach. I followed TurboB and JonL's threads for my build and that largely made me feel more confident in picking my turbo, since its very similar to what they used.

Just shooting from the hip here but jdm turbos are often copied and sold on ebay on the hella cheap. I know Motzingg has seen these, Chinachargers often called. Something meant for a 2.4L 4 banger up to maybe a 3.0L inline six might work out well for the 200 (=3.27L). The larger displacement of the 200 would make up for the lower rpms youd be running. My buddy has used a $150 Emusa turbo on his s13 240sx with no issues for about a year now, running 18psi all the way up to 7-8K rpm.

Just a thought once you get a turbo size in mind.

Thanks guys!

Mech_E - I'd be running premium so 91 or 93 if I can find it here. I've sized it through there. A T3/T4 57trim with .60AR seems to put me right in the center of the highest efficiency island. I'm a little worried about not spooling at low enough rpms. These motors don't rev high. I'm eventually gunna replace the cam but the stock one will have to do for now.

Motzingg - I ran through the calculations for the 200 as I found them on another site and what I've got on that calc matches up close.

I really wasn't asking about max psi to just buy something at that level. It was more of a reference for something to not exceed once I've picked out a turbo.

I'll have to look up their builds. I've been going off the "Idiots Guide to Turbocharging the Falcon 6".

That's definitely in the right price for me! haha When I looked that one up on the calculator it seems way too small a 3.3L. Apparently, from what I was reading on other forums, it's even small on the 1.6L of a miata. I dunno if going for something bigger might be better.

I thought Emusa made a couple different sizes but maybe not. Either way, my goal was just to inform you that the cheap ebay turbo's aren't always so bad. I almost bought one that was a knockoff Holset Hx35 until I found a real one used locally.

Good luck with the build

yeah i agree with the t3/t4 wherever you get it, couldn't tell where you were at budget wise, even the chinacharger route is roughly 2-3x the cost of a junkyard OEM turbo (incl. wastegate and BOV). Especially the Volvo one which is common as heck.

i'm not sure where the numbers are off, once again, because those 'calculators' don't show the math, but 300 hp seems pretty high, especially if you're figuring on the stock carb and log. I think the stock carb is rated something like 150 CFM but i'm not sure what the pressure drop at which they are measuring that is. Even if you can slam 500 cfm through the thing, you're going to be into a very strange place tuning wise... just like most of the other folks have seen trying to do this same thing.

if you cant scrape together the budget to do a proper 300 hp build (rods, pistons, head work, etc) you're probably going to get a more useful and better driving car by setting your expectations and calculations up for what it will actually produce.

either way if you like what its doing, its always cheap to buy a new turbo compared to having to build some crazy motor to make your turbo happy, ha!

heck those chinachargers are cheaper than buying a new camshaft by itself.