Junkyard supercar build questions.

The automotive technology class I teach for inner city kids is building a 5l 32v 928 with near zero dollar investment as the goal (because its all out of my pocket ). The kids are super inspired, learning a bunch, loving the project and its creating a ton of interest in the program, but I think it needs to have turbos to be truly special. The local junkyards are very on board with the project. So what turbos should I use and as for management I was thinking either megasquirt or something crazy like motorcycle itbs with the bike management and a power commander or something. What sayeth the hive mind? Any other ideas as to how to make this thing rock? We're going to take it to track days and have the kids pit and wrench on it when its done, maybe a few car shows, etc.

Wow, that sounds like a heck of a project. Subscribed!

I am interested to know if ITB's can work with boost. My ITB's tune best for driveability under Alpha-N, which would not know if there was boost or not.

Sounds like an awesome project. Got any pictures of the 928??

ITBs work with boost easily (well... besides being annoying in general), since you'll need a plenum for them to work. You'd just tune it via speed density since you'll have a huge reservoir for map signal.

Gixxer 1000 throttles can be had for cheap, and a Megasquirt is going to be what you'll want.

In reply to Swank Force One:

You'd actually use blended mode for ITBs with da boosts. So it's Alpha-N at idle until boost comes online and then it's MAP.

The plenum wouldn't be under vacuum since it won't have a throttle body just an open pipe to the airbox via the turbo/blower.

For turbos, I'd use a pair of Mitsubishi TE04H turbos off the 88-92 Chrysler FWD turbo cars. They are virtually worthless in the Turbo-Dodge world but they are pretty nicely sized for a 2.0-2.5L and will produce upwards of 18psi if over spun.

Plus you can do an Axis powers motif, especially if you use some parts from an Italian car or bike (Ducati ITBs. Perhaps?)

Otherwise nearly any turbos for a 2.0-2.5L 4-cylinder would work great as a pair for a 5.0L V8.

For a single turbo I'd look at Holsets and the like.

BTW, Enginelabs.com had a feature on a 900hp supercharged 928 V8. It was a twin cam version with variocam I believe, but it was impressive!

I'd ditch the ITB's the throttle shaft and blade in the port airflow is a negative (up to) 20% airflow reduction (times 8).

Speeding up and slowing down airflow in the port is like throwing away the best part of a steak!

ITB's are old school vintage race you won't see it on anything new (and fast).

Long Individual runners are nice with a bell mouth and a slight taper down to the port size connected to a large volume plenum. There are formulas for this out in the wild.

A single TB with an IAC bypass solves a lot of drive-ability and tuning issues that accompany ITB's.

Will a pair of td0413t turbos be a good fit? I already have one of those and theyre easy to find because so many volvos are dead with intact turbos. The thought behind itbs was to ditch the complex and questionable factory electronics package in order to increase reliability. The theme behind this build is light and simple, to correct all that is wrong with a 928 while retaining what is right.

The intake on the 32v cars are pretty decent as is... turbos can fit under the engine but it is tight. I would recommend you do something like the 2009 pikes peak car.

The turbo was in front of the engine. Plenty of room. Any turbo off a diesel truck would be decent and cheap.

bentwrench wrote: I'd ditch the ITB's the throttle shaft and blade in the port airflow is a negative (up to) 20% airflow reduction (times 8). Speeding up and slowing down airflow in the port is like throwing away the best part of a steak! ITB's are old school vintage race you won't see it on anything new (and fast).

Sorry OP, not to hijack your thread, but I sense a learning opportunity. If ITB's are vintage, how come so many BMW motors have them? They were on the S38, S65, S85, I'm sure a bunch of others too. Mind explaining?

All rb26dett skylines had the itbs... with boost ! The pulsar gtir had sr20det.. itd with boost ! Jdm 4age from the late 90' had itb... e30 m3, e36, e46, m5...

Would remote mount turbos suck (be laggy)? I could put a pair beneath the (formerly) rear seat area. It'd be pretty convenient compared to the alternative in this application.

turboswede wrote: In reply to Swank Force One: You'd actually use blended mode for ITBs with da boosts. So it's Alpha-N at idle until boost comes online and then it's MAP. The plenum wouldn't be under vacuum since it won't have a throttle body just an open pipe to the airbox via the turbo/blower.

I can't say i've ever seen that done, but i've seen a few tune straight speed density.

In reply to sesto elemento:

How familiar are you with tuning?

Speed-Density tuning is a whole lot easier with turbos and a single throttle than ITBs. If you are familiar with tuning, and have done a alpha-n tune before with ITBs- adding the dimension of boost is still quite complex.

Whereas speed-density is pretty straight forward.

alfadriver wrote: In reply to sesto elemento: How familiar are you with tuning? Speed-Density tuning is a whole lot easier with turbos and a single throttle than ITBs. If you are familiar with tuning, and have done a alpha-n tune before with ITBs- adding the dimension of boost is still quite complex. Whereas speed-density is pretty straight forward.

3-4 out of a possible 10 maybe I can enlist some help though and am excited to learn.

If this is for kids i would do some flash with performance. Big polished single turbo right up front where everyone can see it, big intercooler up front, megasquirt with a windows tablet dash, flashy race seats, big diy front splitter and big rear wing, loud exhaust, and racy graphics. This should all try to happpen on a challenge budget and shoot for 500hp. Man, now I want to build it.

The plan for paint is white with plastidip snow camo, junkyard turbos for mufflers so it'll sound like war. We've already gutted the interior but minimalist everything else too, hopefully poly windows etc. It will be the absolute minimum for being street legal in mass (and maybe soon n. carolina). As far as aero goes, I'm pretty good at metal fab and the front splitter is damaged so I might fab up something a bit more aggressive.

It was delivered within seconds of my daughter so I was thinking that the universe wants it to be her fist car .

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arrived at the same moment as

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So I figure that I've got 16 years to get it sorted out so it'll be safe and reliable. I also figure that regular cars will be fast in 2031 so it'll need some boost

sesto elemento wrote:

alfadriver wrote: In reply to sesto elemento: How familiar are you with tuning? Speed-Density tuning is a whole lot easier with turbos and a single throttle than ITBs. If you are familiar with tuning, and have done a alpha-n tune before with ITBs- adding the dimension of boost is still quite complex. Whereas speed-density is pretty straight forward.

3-4 out of a possible 10 maybe I can enlist some help though and am excited to learn.

Don't do boost with ITB's then. It would end up being incredibly complicated to tune well. You and your team will learn a LOT about tuning just doing one throttle. On top of what you will all learn with the project.

In reply to sesto elemento: I used junkyard turbo's in the past. The trick is to use a magic marker to mark one blade and then give it a really good spin and mark where it stops.. if it repeatedly stops in the same area the turbo isn't usable anymore.. get a different one.. Don't try to use a megasquirt..Too complex! Just buy a FMU (Fuel management unit) They used to sell for about $85 new and about $50 used.. What it does is increase fuel pressure as boost builds. No it's not perfect but it's a whole lot easier to convert a non-turbo unit to turbo.

edwardh80 wrote:

bentwrench wrote: I'd ditch the ITB's the throttle shaft and blade in the port airflow is a negative (up to) 20% airflow reduction (times 8). Speeding up and slowing down airflow in the port is like throwing away the best part of a steak! ITB's are old school vintage race you won't see it on anything new (and fast).

Sorry OP, not to hijack your thread, but I sense a learning opportunity. If ITB's are vintage, how come so many BMW motors have them? They were on the S38, S65, S85, I'm sure a bunch of others too. Mind explaining?

There's nothing old-school about ITBs. Most new race cars (such as all F1 cars) and sportbikes have them...the latest R1 has ITBs with variable trumpets and both port & gantry injection!

This Might help. I would go for the holset turbo from a cummins ram, it makes big boost while being reliable. Sure, it's a bit laggy, but if you want to make big power while being reliable, that's what I would go for.

In reply to GameboyRMH:

However, the GTR (new one) just uses two TBs. One per bank. Both are fine. ITBs are certainly going to be more complex.

In reply to frenchyd:

Since this is a long term project, complex shouldn't be a problem. An FMU to me is like telling someone to just use carbs over fuel injection because it is easier. It might be, but easy doesn't make it good.

let me know if you decide to run a single turbo, i may be able to get you a hx35 or hx40 equivalent for the cost of shipping. it may or may not need rebuilt but thats just another learning experience for them

In reply to sesto elemento : any turbo will work, the only question is how well, how much boost?  

When you go junkyard shopping here is a trick that will help you find good ones.  Take a magic marker and mark one fin. Give the impeller a full spin and mark on the housing where it stops. Now spin it again and mark it again after 4-5 spins a pattern will start to emerge. A really good one will have a fairly random pattern one on the way out will stop about the same place every time.  

Don't forget to get the cooler with the turbo

Also you have to open the ring gaps up. If you are happy with about 6 pounds of boost .002 ought to be enough. High mileage engines might be approaching that.  However .004 extra ring gap is. Needed if you really want to run hard and long safely with higher boost