Torn on how to proceed. Need advice for winter project

[phillysrt4]

Hello everyone!

Well, I have acquired a 1990 LX convertible roller in great shape. Subframe connectors already in place, legal rollbar, etc. My problem is I am torn on how to proceed. I have been doing a lot of searches and reading on different and novel powerplants that can be put into the engine bay.

When it comes to the powerplant, here are some of the criteria I am using in the selection process:

1) Novelty - Is it a relatively uncommon swap?
2) Power Adder - How does it take to power adders (turbochargers in particular)?
3) Performance Aftermarket - how much is out there and how much does it cost?
4) Initial cost of acquisition
5) Amount of custom fabrication - is it a bolt in swap, or do I need a machinist every step of the way?
6) Engine configuration - I have a STRONG preference to OHC versus OHV. Maybe its from previous cars I've owned, but I like the idea of being able to spin the motor to 7000+ RPM

So, given all this, I have come to the following choices for a swap:

1) 2.3 liter lima based turbocharged SOHC
Pros:
-Bolts right in
-I already have some parts (cylinder head, intake/exhaust manifolds, turbo to get it up and running, etc)
-Cheapest bulletproof rotating assembly of any of the options I've looked at, even if I go to a 2.5 stroker.
-I've already taken one of these apart and I have the most knowledge of this engine versus any other being considered.
-Relatively Uncommon
-Off boost Id get the fuel economy of a 4 cylinder car (30 mpg give or take)
-Several kits to convert it to EDIS ignition to use with standalones such as Megasquirt to allow both fuel AND ignition control.
Cons:
-The cast iron head doesn't have the flow of later SOHC designs on their bigger engines. This means extensive porting and machining to the head will be required for bigger valves, higher lift cam, etc.
-Probably limited to 425-475 horsepower without going with a $2000.00 aluminum head from Esslinger

2) Twin turbo 3.8 liter OHV v6 from 99-04 base model mustang.
Pros:
-Still a relatively bolt in process
-Still relatively standalone (i.e. Megasquirt) friendly
-Plenty of room in the engine bay to accomodate a twin turbo setup.
-Still get good fuel economy when off boost
-Heads flow better compared to the 2.3 limas
-Very uncommon swap.
Cons:
-OHV. Granted I dont know as much about it as I guess I should, but I just cant see spinning an OHV car to 7k RPM, even with hardened pushrods.
-Expensive performance parts. It seems the few places that do offer upgraded parts seem to charge quite a bit for them.

3) Single or twin turbo 4.6 or 5.4 mod motor
Pros:
-Relatively large aftermarket. This means getting forged parts are going to be cheaper than the other options.
-Is still a bolt-in process (with correct k-member).
-No need for aftermarket standalone since Ford's computer has tons of 3rd party tuning support
Cons:
-Desired/popular swap
-Large size of motor versus the 5.0 or lima block means space is at a premium, possibly nixing the possibility of a turbo setup.

4) Single or Twin turbo 4.0 SOHC V6 (as found in Navigators)
Pros:
-OHC. No qualms with spinning it up
-Relatively cheap to get one out of a wrecked vehicle
-Enough aftermarket to really beef it up.
Cons:
-Expensive aftermarket
-Not a bolt in process whatsoever. Fabrication is going to be required in ways where it might be more trouble than its worth.
-I have no idea whether its feasible to use a standalone with this or if I have to source a computer. No knowledge of tuning aftermarket for this motor.

I will NOT put a pushrod 5.0 back into this car. Period.

Give the above, I am leaning toward the 3.8 v6. If someone can point me to empirical proof that this motor can be worked to spin above 5500 without grenading, it would make it a lock. Second choice is the 2.3 lima. Yeah, I'm going to be playing second fiddle to the cars in the 10.00-11.49 bracket, but its going to be a relatively cheap build.

If anyone has any suggestions or insights into these options I would greatly appreciate it. I want to formulate a plan and actually start buying parts no later than the first weekend in October.

Thanks.

[Steve-0]

Well I know for a fact that my brothers 3.8 easily spins to 6200-6300. I'm not sure what the limitations are, you could probably ask him. We are getting his car tuned at SGS on wednsday, so new turbo numbers should be up soon.

[phillysrt4]

Id be curious to hear about it. 6200-6300 with stock pushrods means I can probably get close to what Id like with hardened ones. That really puts that back on the table and 3.8 v6's are dime a dozen at u-pull its.

[5k#Eaton]

cool project

[phillysrt4]

Thanks!

Ive been wanting a RWD project for quite some time now that my neon is getting up in miles and Im tired of fighting the problems of FWD cars in races from a dig. I want to feel that neck jerking 1.5 60' launch. I'm sick of being frustrated at running in the 12's despite a 118 trap because I cant get a 60' under 2.0.

There are two things I'm a big fan of: Forced induction and computer controlled fuel injection. I can calculate turbocharger size to meet the power goals of any engine in my sleep, and with the 2nd generation processor thats in the current Version of megasquirt, you get all the features you would want in computer controlled fuel injection and ignition timing. Things like 12x12 fuel and spark tables, wideband support, data logging, tuning with your laptop, support for turbochargers and nitrous, etc. The best part is if you can solder you can put one together and the kit is under $300.00. I'm pretty much set on using this to control the motor.

I think I'm going to need some maching work on the cylinder heads and possibly some custom header work, so I'm going with one of the vendors here I already PMed a few weeks ago.

I'm probably going to size up the turbos so that I can peak out in the 475-550 hp range with a nice fat area under the torque curve. That means I can probably save some money and use T3/T4 hybrid journal bearing turbos. Then I can use the money I save toward machining work.

[Viper_ed]

Save your money to feed the horse pulling your buggy some better oats so it's not so tired after plowing the field all day!

[Pure Stock]

Save your money to feed the horse pulling your buggy some better oats so it's not so tired after plowing the field all day!

[Chris00GT]

I'd go with a built 4.6L DOHC with a single 76mm turbo. I got the chance to ride in a 2003 Mach 1 with this combo and a built motor and the car was stupid fast on the street. The car just kept pulling, it was just unreal and sooo fun!!

[phillysrt4]

Save your money to feed the horse pulling your buggy some better oats so it's not so tired after plowing the field all day!

at least mine are horses, not ponies

[phillysrt4]

I'd go with a built 4.6L DOHC with a single 76mm turbo. I got the chance to ride in a 2003 Mach 1 with this combo and a built motor and the car was stupid fast on the street. The car just kept pulling, it was just unreal and sooo fun!!

Yeah that was the other consideration. My only concern is the relatively cramped bay with the 4.6 mod motor in there. Cam's engine bay looked pretty packed.

Im pricing out all the options and I'll see where the money versus originality versus power potential puts me.

[SV1000s]

I'm still partial to the 5.4 DOHC swap!

[SonofaBish]

i'm going to get flamed for this but if you're not hell-bent on a ford motor,

single turbo LS1

nuff said... lol

OHV and can easily spin into the RPM range you're looking for... in a light ass foxbody, would make a hell of a powerplant

[somethingclever]

If you go turbo I wouldn't bother with twins. A nice single setup would be fine for a street car.

[SonofaBish]

If you go turbo I wouldn't bother with twins. A nice single setup would be fine for a street car.

I think the only reason to go Single on a street car is easier piping/build... depending on the power goals, twins will make more power in the street friendly RPM's... will take a lot of RPMs to spin a big single... but if power goals arent too rediculous, i agree, a single 76mm turbo will make good power and still spool at a decent rpm

[somethingclever]

I think the only reason to go Single on a street car is easier piping/build... depending on the power goals, twins will make more power in the street friendly RPM's... will take a lot of RPMs to spin a big single... but if power goals arent too rediculous, i agree, a single 76mm turbo will make good power and still spool at a decent rpm

Practically half the piping and half the cost. Spool time is negligable whether you're roll racing OR at the strip. Regardless....a single sized the same as twins will really have nearly the same spool time. Only time twins is really needed is when there's no room for a single 5" dp. :)

[SonofaBish]

Practically half the piping and half the cost. Spool time is negligable whether you're roll racing OR at the strip. Regardless....a single sized the same as twins will really have nearly the same spool time. Only time twins is really needed is when there's no room for a single 5" dp. :)

half the piping, but not half the cost (i could be wrong though if there is LOTS of room in the engine bay)... and i dont' agree on the spooling... my turbos begin to spool before 2000rpms and push max boost just past 3000 rpms on a crap tune (final tuen should be done tonight)... so i expect it to be fully spooled around 3K - maybe less... Even on a 348 you can't get a large single to begin spooling anywhere near that quick, let alone a smaller engine (if he goes with a 4.6 or 5.0) ... my turbos are pretty good sized, and they're journal bearing - so BB would be spooling even quicker...

however, as i posted

i'm going to get flamed for this but if you're not hell-bent on a ford motor,

single turbo LS1

nuff said... lol

OHV and can easily spin into the RPM range you're looking for... in a light ass foxbody, would make a hell of a powerplant

I think single is the better choice in this matter as well...

[somethingclever]

half the piping, but not half the cost (i could be wrong though if there is LOTS of room in the engine bay)... and i dont' agree on the spooling... my turbos begin to spool before 2000rpms and push max boost just past 3000 rpms on a crap tune (final tuen should be done tonight)... so i expect it to be fully spooled around 3K - maybe less... Even on a 348 you can't get a large single to begin spooling anywhere near that quick, let alone a smaller engine (if he goes with a 4.6 or 5.0) ... my turbos are pretty good sized, and they're journal bearing - so BB would be spooling even quicker...

however, as i posted


I think single is the better choice in this matter as well...

I meant close to half the cost in parts (1 turbo, 1 wg, 1 oil line/drain..etc) and labor (1/2 pipe to fit and weld). I'm not putting down anyone with twins...it's just not necessary on a street car IMO. Saying your car starts spooling before 2k is great...but saying that a single turbo sized to your engine with the same airflow capabilities as the twins will not start to spool anywhere near 2k rpm is unsubstantiated...since you haven't made that comparison. (unless you're going to start another turbo build!! :D) But this topic in general can be a thread on it's own....i don't want to ruin his thread.


Philly...if you want to be different...don't do a 2.3t....that's my next project..LOL

How about an yamaha SHO drivetrain @ 9k rpm???

[Viper_ed]

How about an yamaha SHO drivetrain @ 9k rpm???

With QUAD TURBO'S!!! Now that would be different!

[phillysrt4]

I really dont mind all the back and forth in the thread. People are bringing up very useful points and worthwhile things to consider.

To address a few things I saw in the thread today:

1) I did consider a 2.3T but Im concerned that I'll be forever stuck in 12 second territory. I want to trap over 120 (preferably over 125) and I'm uncertain if I can get the flow out of the iron 2.3 head that I want. If I'm going to spend 2 grand for an essy head, I might as well save 500 bucks and get some work done on the 3.8 heads. the money I save would go a long way toward other parts.

2) With respect to spoolup on twins versus a single turbo, the answer pretty much is "it depends". Lets say I want to really go for it and shoot for at least 600HP out of the motor. Suppose I decide I'm willing to spend the money and go with ball bearing turbos (well not really, but they're handy compressor and turbine maps so its easy to reference). Hitting 600HP means approximately 70lbs of airflow. That means an 88mm turbo, at a minimum, is going to be required. Consider the Garrett GT4088R turbo. If you look at the turbine maps, the smallest AR they have is a 0.85. To hit "full spool" (which I would consider getting past the knee of the curve) means over 30lbs of exhaust flow.

On a 4.6 or 5.4 mod motor, I dont think this is going to be an issue at all. In fact, I would consider the 0.95 or 1.06 AR turbo in the GT40 housing so that I dont have insane backpressure up top. However, I think the 3.8 might be sized a little small to get a fast spool even at the 0.85AR housing. This is all "a priori" in that I havent done a formal calc on the exhaust flow, just a guess.

However, if you divide the 3.8 or 4.6 mod motors in half, then you're right at a displacement I'm comfortable with. Getting 35lbs of air (since two would give 70) is relatively easy. You can go with something as small as a 60mm turbo to get this kind of flow. The 60mm turbos come in two or 3 different kinds of exhaust housings with AR's as low as 0.48 IIRC. I think you're going to get that small turbo spooled up alot faster in 1.9-2.3 liters of displacement than you are that single 4088R. Moreover, DBB pricing i've seen shows that two of the smaller turbos are going to cost less than that single GT40R.

Im going to have to do a more formal analysis on the exhaust maps, but given what I've seen out there and given the trend for companies to cater to the "sport compact" market with respect exhaust housing sizes and AR's, I think you're going to have a better shot at getting a pair of twins to spool up lower than a larger single.

3) I'm considering twins even though they're not needed for a street car because its something different and relatively uncommon. Can you think of a single SCS user with a twin turbo 3.8 v6? Single turbo yes, but not twins.

[SV1000s]

and expensive....but original nonetheless

referring to the Yamaha mill