Minivans are Hard To Go Fast In / TBI Bottom Ends Cant Handle Turbocharging

So I mentioned that i had converted an internal Walbro 255 to an external and added it inline in the engine bay. The longer version of the story was that I replaced it with a cheap Rockauto pump based on nasty noises it was making. The noises turned out to be a symptom of a fluctuating level of pump strainer blockage coming from sediment in the tank.

After I corrected that issue I began to suspect that this used Walbro was perfectly fine and could be used again. I installed external inline pumps on the last two TMs i fixed up (Lancer and Spirit) after learning many years ago from Ondonti about how inline pumps suffer much less loss of volume/flow at high fuel pressures even compared to large/powerful single pumps like a Bosch 044. I wanted to install an inline pump on the van but didn't want to spring for anything if i could make this Walbro work. I had installed a used Walbro 255 external on my Lancer Shelby and the only differences i noted were a different case crimped over the pump body with suitable inlet/outlet fittings tapped into it. I suspected i could adapt the internal to work as an external if i could do two things: 1. Adapt a 5/16 hose barb to the rather large opening on the suction side, and 2. Defeat the ~75psi bypass/relief valve that the internal-style Walbros have (Ondonti tipped me off to this as well).

I had recently bought a 1/2 NPT tap to tap Acannell's 4th cylinder cooling plate for a 5/8" hose barb for this engine, and i noticed that the plastic 'inlet nipple' on the Walbro could be tapped for a 1/2" NPT fitting. I took a 1/2" NPT plug, tapped it for a 1/8" NPT fitting with a 5/16" hose barb, and screwed it into the pump inlet. I suppose it's odd that i happened to have these necessary pieces, but it worked out well.

For the relief valve, I had heard that some people simply smash the valve (a ball bearing) down into it's seat and then epoxy over it. I engaged my junk scavenging skills again and found some odd little screws that formed a very tight seal with the opening for the relief valve. I smacked the ball down into its seat and screwed the screw in on top of it to hold it shut. I have seen no evidence of leakage at either end of my halfassed inline pump with fuel pressures up to 75psi so far.

Unfortunately I didn't take pictures of the inlet end, but I can get them and edit them back into this post. Here's a pic of the Bypass Defeat Screw, though.
Attachment 58115

As for wiring, this pump is 'mounted' to the passenger strut tower, with power coming from the the coil positive terminal and ground being a ring terminal under a screw on the firewall.

I miss seeing this van all the time. And it's absolutely a riot to drive with race gas and all the boost.

I never will forget that sound and feeling of it bottoming out and your only response being wild laughter.

I drove it to work yesterday. Posted about it on GRM today. Love the damn thing.

I didn't notice much when I was running higher boost but lately since I haven't been monitoring anything and the weather's been affecting my boost settings I turned it back down and noticed it is spiking hugely. I think i'm going to port another mitsu turbine housing on the wastegate orifice and swap it on.

Or there is another part of me that says hurry up and start running e85 through it and let it spike however it wants.:evil:

My vote is turn the base pressure up, e85 and plug the 2nd stage back in. Let it eat! I swore I saw a 20PSI spike in 4th when I got to drive it but it might've just been CO poisoning from the Jeep I drove.

Good stuff Vigo

I am taking this van to GRM $2016.

After reading this thread, I'm contemplating turboing my TBI. Although, if I already have the head off, I might as well throw the turbo pistons in.

Quote:

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Originally Posted by Vigo

So I mentioned that i had converted an internal Walbro 255 to an external and added it inline in the engine bay. The longer version of the story was that I replaced it with a cheap Rockauto pump based on nasty noises it was making. The noises turned out to be a symptom of a fluctuating level of pump strainer blockage coming from sediment in the tank.

After I corrected that issue I began to suspect that this used Walbro was perfectly fine and could be used again. I installed external inline pumps on the last two TMs i fixed up (Lancer and Spirit) after learning many years ago from Ondonti about how inline pumps suffer much less loss of volume/flow at high fuel pressures even compared to large/powerful single pumps like a Bosch 044. I wanted to install an inline pump on the van but didn't want to spring for anything if i could make this Walbro work. I had installed a used Walbro 255 external on my Lancer Shelby and the only differences i noted were a different case crimped over the pump body with suitable inlet/outlet fittings tapped into it. I suspected i could adapt the internal to work as an external if i could do two things: 1. Adapt a 5/16 hose barb to the rather large opening on the suction side, and 2. Defeat the ~75psi bypass/relief valve that the internal-style Walbros have (Ondonti tipped me off to this as well).

I had recently bought a 1/2 NPT tap to tap Acannell's 4th cylinder cooling plate for a 5/8" hose barb for this engine, and i noticed that the plastic 'inlet nipple' on the Walbro could be tapped for a 1/2" NPT fitting. I took a 1/2" NPT plug, tapped it for a 1/8" NPT fitting with a 5/16" hose barb, and screwed it into the pump inlet. I suppose it's odd that i happened to have these necessary pieces, but it worked out well.

For the relief valve, I had heard that some people simply smash the valve (a ball bearing) down into it's seat and then epoxy over it. I engaged my junk scavenging skills again and found some odd little screws that formed a very tight seal with the opening for the relief valve. I smacked the ball down into its seat and screwed the screw in on top of it to hold it shut. I have seen no evidence of leakage at either end of my halfassed inline pump with fuel pressures up to 75psi so far.

Unfortunately I didn't take pictures of the inlet end, but I can get them and edit them back into this post. Here's a pic of the Bypass Defeat Screw, though.
http://www.turbo-mopar.com/forums/at...id=58115&stc=1

As for wiring, this pump is 'mounted' to the passenger strut tower, with power coming from the the coil positive terminal and ground being a ring terminal under a screw on the firewall.

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Those "odd little screws" are PC fan screws.

Maybe they came with the 7" PC case fans i have zip tied to my intercooler!

Very good collection of ideas by Vigo! I finally got the Sundance running and took it to the track tonight. It now has a fresh .030 over balanced 2.5 with the shafts removed, the trans is a A523 with the 3.50 gear. With M&H 23"/7.50/15 on it, even with no intercooler it is a blast to drive. I added a gallon of VP109 to about 3 gallons of Chevron 92 and did a best pass of 14.15 with a best speed of 95mph. The best 1/8 mile was 8.96 at 78.9. I'm pretty interested in getting some cam keys to try retarding it, I was having traction problems in 2nd even with the slicks at 18lb pressure. I know the car has more, but it did well for the first time out. The last time I drove a stick at the drags was back in the '70s....

That's pretty good for no intercooler, huh! What was your boost level?

As far as the slicks, i believe i have the exact same. I've run mine below 15psi on heavier vehicles so i think you can drop a lot of pressure to hook up better. When i ran mine near 20psi i was able to spin them off the launch with my old 3.0/5spd dynasty if i let the clutch out too fast. In my opinion ~18 psi is actually overinflated a bit.

I believe i have two NIB sets of mopar cam keys, but i only know where one set is offhand. If i can find my 2nd set i could send you one of them.

As for the van, we have 'started' working on it for GRM challenge. Did a little weight reduction last weekend and going to do some more work tomorrow. I'll post more when i have more to say, next week.

Thanks for the tip about the slick pressure, I'll lower them a bit more next time. Boost level was 17-18 lbs, tapering off in 3rd and 4th to 15-16. My best 60' times were 2.0x, worst was 2.29. I had an old Dawes A/F meter on the shelf, so I put it in. It showed green while pulling in 3rd and 4th at 6K crossing the line, and the plugs looked fine after the runs. Minor mods I'll be testing, I put 2 hard rubber spacers in the driver's side rear coil spring, in an attempt to throw a bit more weight to the passenger front. I also was only running 10^ of timing, so I bumped it up to 12^. I'll look forward to your next posts! If you find the extra set of cam keys, I'll be happy to pay you for them, it would be fun to help fund your GRM challenge.

When i was running mine on race gas i actually ran 20psi AND advanced base timing, but i have an intercooler and you don't (yet). I am surprised that this mitsu seems to be one of the 'healthy' ones since ShelGame has said that once you spin them too fast they self-clearance until they don't seal up well enough to make higher boost numbers. I guess yours might have a bit more wear on it? Ultimately you can figure out how close you are to its max potential by putting your trap speed and race weight through a horsepower calculator. When i did that with this van it came out around ~230chp. I think you have a bit more to unlock if you care to risk it, since as you probably know Terry Ryan ran a 2.5/t1/5spd sundance to 13.3@99.

I forgot to look for cam keys today, i will try to remember in the next few days.

I did work on the van some more today. Lost a little weight and gained a little lateral support going from power van seat to manual shadow seats. Added 1g dsm bov. Removed the last of the old stereo system amp wiring. Mounted a nitrous bottle. :eyebrows:

Need pictures of the internal to external pump mods. Interested in larger external pumps for a few vehicles than the 255 walbro offers. I don't get their failure to improve external offerings. People seem enamored by Bugatti Veyron style pumps (called 330lph walbro) but don't flow much more than the 255 and the company (piersburg?) Was bought out by walbro. The good true Veyron pump requires a controller

Worked on the van some more today. Installed a wideband. Always wanted to put a gauge here and figured i'd use this as a test run before cutting anything on the nice van. Went ok.
Attachment 59241http://www.turbo-mopar.com/forums/at...chmentid=59241

Also made a 3" downpipe, sort of. It's stock 2.5" for the first 5" or so. Needed something to stick a wideband into since i took the stock exhaust out. I'll add a muffler after the challenge for more street driving.


Started working on the nitrous setup. It's a single nozzle wet shot into the intercooler (!?). It's powered off a relay activated by the ~4k rpm switch. It's triggered off WOT switch under the pedal. None of that is finished but all of it's in progress.

Ordered a hardware kit for the OBX. That's going to be installed in the coming weeks.

Got a bigass piece of plate to build the lowering plates to bring the rear down more.

Ordered the wheels. FEDEX tried to deliver them to my house twice already.

Can you list all of the mods you've done so far and the current specs of the engine/setup?

Thanks! I love this build so much!

Well, almost a week late in posting, but my teammate and I successfully ran in and returned from the Grassroots Motorsports Magazine $2016 Challenge with this van.

The GRM Forum (great, great community!) for the last 2 years at least has been inventing themed sub-classes for the Challenge. Last year (iirc) it was the Aristocrat class where people bought ratty luxury cars (LS400, Q45, BMW 750 etc) and entered them in the challenge. This years sub-class was the Soccer Mom Challenge for minivans.

I had been planning to attend this challenge since about this time last year, but the minivan sub-class didn't become 'real' for several more months, so we kicked around ideas for some of my other cars like a Miata i had and later a Porsche 924. When the van class become 'official' i decided it was probably a one-time opportunity i couldn't pass to race and mingle with other low-dollar minivan enthusiasts. There's not really any other event outside of a TM/TD gathering that would bring people like that together. Luckily this van has been complete and drivable for basically this entire year so all that was needed were small mods that didn't require major tear-down or build-up. Our prep was pretty relaxed.

We flat-towed the van to the Challenge behind my Lexus GS450h (which currently has mismatched wheels due to an ordering goof on my part) so just like my last challenge attempt, i truly pulled up in my own particular style. :p

The van ran flawlessly throughout the event. We blew one charge coupler apart and had to reseat it, and we lost some oil when the oil cap flew out on the autocross course. Other than that, all we had to do to it was wheel/tire changes and drive it.

Unfortunately only 2 other vans showed up. I was substantially faster than them in both autoX and drags, but came in 2nd in the van class due to the sheer ambitiousness of one of the other vans which was basically a van body swapped on top of the unibody of a totally different car. I'm pretty ok with that as I would have felt a little bad about taking the van win with a real pile of ---- van that wasn't even built for this event or run to its full potential (at least in the drags).

I have a lot more pics and details but here are a few for now. I'll try to flesh this out better sometime soon.
http://i279.photobucket.com/albums/k...29375614_n.jpg
http://i279.photobucket.com/albums/k...72073910_n.jpg
http://i279.photobucket.com/albums/k...9790_n%201.jpg

That's awesome Vigo! Was the van pretty good at slumming through corners?

Way to go! Was wondering how you made out.
In for more pics when you get caught up.

https://grassrootsmotorsports.com/ar...016-challenge/

http://i279.photobucket.com/albums/k...77331457_n.jpg
http://i279.photobucket.com/albums/k...7/AWN_0443.jpg
http://i279.photobucket.com/albums/k...7/DSC_0273.jpg