So I'm gonna try out a "junkyard" turbo build as a small project to get my feet wet, so to speak. After quite a bit of research and calculations I think I've got what I'm looking for but I'd like to make sure I'm on the right track.

This is for a f22b1 on a 5th gen accord. I'm looking for an Autox/dd powerband. So low/mid torque, quick spool and relatively low psi due to stock engine internals (+/-10psi)

My calculations figure peak torque at 4k with 10 lbs/min at 10psi. That should give a pretty quick spool for low range but not starve the engine up high.

The best turbo I found is the Garret gt20 off a Saab 93.

Here's the info and compressor map I found on it.

Garrett GT20 - GT2052 - 52 TRIM - 225 HP ? Turbocharger Specs

If I'm reading the map right, this should give me a good starting point and even maintain decent turbo efficiency up to 16lbs/min and 7000rpm.

Let me know if I'm understanding this right. And if you know of any junkyard turbos that would work better.

Thanks

 

:/ guess another person didn't read the FAQs , or at least not correctly.
16lbs/min is 160 hp rofl, pick a power goal and find a turbo that can achieve it, watch some tutorials on how to read a compressor map. I can tell you right now that you're probably looking at a 50 or 57 trim t3/t4.
.64a/r

 

I actually did read the FAQ. It's been one of the 6 or 7 tabs simultaneously open on my browser the past few days.

However, I calculated the estimated power against the psi and got just about what I wanted. Around 200hp. So I've read the compressor map and just want to make sure that I'm understanding what I've read correctly since a few things are kinda confusing me.

 

The problem with a small weird flanged turbo is the manifold would have to have the accepting flange for it aswell. Much easier to start with a small .42/,48 t3 framed turbo, Id even try an ebay 45 trim @ $120 new on a build like this on a $70 cast manifold. Spool would be near instant and carry to redline

 

Searching around, ebay turbos had a pretty bad rep- which is why I was looking around for a used OEM. But i'd very happy to get one if you know what I should be looking for. I wouldn't mind replacing internals with better components if that's what it takes.

But as far as the manifold goes, I will be making my own and so I can fabricate any flanges needed. The cast manifold is appealing but from various dynos posted on the subject, it looked like short, equal primaries without sacrificing low end would be best for broad range power whereas the log manifolds choked up top. I designed a manifold with 1.6" ID 12" Length 4 into 1 primaries that should give a good response.

I don't know how much it helps but a typical Autox track pull for me is 1st gear 2k-5k starting out and then 2nd gear 2500 rpm to 4k mostly for basically the entire course. Maybe 1st at hair pins.

 

It seems you've failed to take in to account the volumetric efficiency and airflow of the base motor.

The F22B1 is a 15lb/min motor in stock form so you'd benefit almost nothing from running such a small turbocharger. Also even the sohc vtec motors have fairly high VE so the exhaust gas mass from a high rpm 2.2l motor would choke the turbine side in a heartbeat leading to high pre-turbine backpressure, high EGTs, and possibly even exhaust reversion into the cylinders. None of these are good for power production or efficiency. The motor these turbos were designed for were low rpm, low VE motors and the turbo systems ran low pressures, like 8psi or less.

Also show me the exact turbocharger you're looking at. The only Garett units Saab used were the GT1752 and a version of the T25 turbocharger. None to my knowledge ever used a GT20 variant. Some Saabs ran small trim T3 turbochargers but the GT series turbochargers didn't exist in the early 90s so there's no way you're looking at a GT20.

In order to make even a slight increase in power you'll need to run something no smaller than a GT2560 or GT2860. Even then those options are small, even for autocross, and certainly won't produce anything outside of the low to mid rpm range.

I'm not familiar with the B variant but in general the F series cylinder heads are high flowing (Stock A1 head flows like a vtec B series) and are known to spool fairly large turbos very fast for the displacement so running a very small turbocharger will ultimately do more harm than good. Especially if you put a decent cam and k series intake manifold on your motor, it will improve low end power but only cause things to choke even sooner.

 

15 lb/min at redline. Maybe I misunderstood the instructions. I was estimating air intake for peak power, not peak rpm. If that's the case I would go 16 lb/min.

I should also mention the existing mods... f23 intake manifold and CAI and a 2.25" exhaust.

The VE I used was 85%, I thought it'd be conservative. The f22b1 is said to flow as well as the a1 until up high but is more design for low end torque and fuel economy. So think D series if I understand right.

Heres the turbo, its the newer gen of 9-3's. 03-10 which are 2 liter engines. I've driven one around. It's a heavy car and there is some turbo lag.
http://www.ebay.com/itm/2002-2010-OEM-Garrett-GT20-Saab-9-3-B207L-12755106-Turbocharger-/321806256381?hash=item4aed25c8fd&vxp=mtr

 

Bro, like I said before, you read the faqs wrong. If you are really shooting for only 160 hp then why the **** turbo?
Trust me I studied the **** out of the faqs and google when I first came here and decided a power goal and tried multiple equations to find out what turbo would be best. I asked for help and presented my equations, which were good and all but you can't really be 100% comprehensive. I found out from advice and I guess other's lack of knowledge of the equations (which I looked up, nothing special that I know) that it's just better to base it off the basic ideas of plotting a compressor map and basing it on what has worked well for others. A 50 trim for example, will pull very hard for your autox, is cheap, and still will produce upwards of 350-400whp.

 

Also peak airflow doesn't occur at the rpm limit, it occurs where the motor makes the most power, which on an F series isn't anywhere close to max rpm so you have to factor the power curve of the motor into your airflow and compressor map calculations.

It's much more complex than you think. After a while you can do it solely from memory (took me a few years) but it requires a great deal of calculations to come up with a suitable pressure/airflow curve to map an engines entire operating range on a compressor map.

If you're only plotting a single, maximum pressure level across the rpm range on a compressor map then you're only plotting the wide open throttle operation on the map. The trick to proper sizing is to plot various pressure points across the rpm range, so like 5psi from 2k to red line, 7psi, 9psi, etc. That will show you how the turbocharger will behave at various loads and rpm. This is beneficial to seeing if you'll encounter a surge or choke condition, especially surge as it can occur mainly at lower pressures and rpm ranges.

Also remember that the turbine side is equally, if not more important than the compressor side. You can't make power if you can't get the exhaust out of the motor. Just because the compressor map is optimal doesn't mean the turbine side will work. Trust me that you'll run into issues trying to run a GT20 turbine side on an F22 motor, regardless of the intended application. The wheel size and housing a/r is simply too small.

You have to look at a turbocharger as a whole an remember that the turbine side and compressor side are matched for a reason and will only behave a certain way, you cannot get around that and the limits that are inherent with a compressor/turbine pairing.

 

Ok. Thanks for the help guys. I think I got a lead on where to go next.

 

I helped tune a T25 F22 CD5 once. It spooled up pretty much instantly and then fell on its face not too much later. Probably 200-220whp. Torquey as hell though.

 

Yea I would imagine before 5k it was done, more like 4-4500 probably.

You have to look where the motor make peak torque and peak power as that's likely where peak VE/airflow occurs so base turbo sizing off of that.

 

If you're gonna pull one from the junkyard I'd honestly just get one of the "nicer" ones from eBay, like a t3 with a small trim, there are a couple on eBay that show videos of them actually calibrating and balancing the turbos unlike most of them on there. I have a friend who got the godspeed one and he said if you lie and tell them you're a company who wants to check out the quality of the turbos before you order way more they will give you a good one lol...

 

Hmmm that's interesting...
While I'm not going to completely bash for going this route, imo getting a legit turbo is probably the most important part for a build, seeing how it's the only thing that really produces the power (intercooler is a factor as well, but mostly the turbo)

I think there's absolutely nothing wrong with grabbing a piping kit from ebay, though I've never tried one myself, probably just grab a universal and cut the pipes whichever way you need them for your setup. Ebay intercoolers I've hear work fine, and the bovs and wgs work alright as well. Probably should stick to the cast manifolds, anything else and you risk cracking and I've heard of metal shards ******* up the turbo.
Other than godspeed cxracing and emusa are the only other cheapo brands that I've heard anything good about, may try them out on a future project but for now I have my full race kit