What should I do

Okay so I have a 1965 mustang 3 speed 200 I6, and rather then cramming a V8 inbetween the fenders and giving my dad a heart attack I decided to do it with a I6. LOL So my goal is to put out 200-250 hp and to have some where around 25 mpg because I will have to drive this every day. I've read alot about different heads and all sorts of stuff, but for some who is on a budget what should I do? Also should I swap out for the 250 or can the 200 handle the job? I know this topic has probably been beat to death but help out one more kind who wants to put his old dads 76 trans am is its place. thanks

200-250hp seems pretty ambitious for someone on a budget, your probably gonna need a turbo to get there. i would think a 250 would be a better start since your starting with more cubes but fit may be an issue. and once your making that kind of power your prbably gong to be a long way away from 25mpgs

Personal opinion here, but...

That Mustang is a pretty light ride (2,600 lbs?), so a warmed over 200 would probably be pretty easy.
None of this is really going to be cheap, but a fresh engine with a good head (aluminum from Mike at ClassicInlines?) a decent cam. a DS-II or DUI ignition, and a 2 bbl carb should wake it up.
The nice thing about it is that you can drive it while you build the new engine, and then the swap is a matter of a few days with the exception of the exhaust work.
You could even leave the stock exhaust system for later, knowing there would be some sacrifice in dialing it in twice.

Benefits:
Easy swap (everything except carb linkage should fit like it is now, A/C, alt, PS, etc).
Stock cooling will be adequate in most cases.
Parts are readily available.
No tranny fitment issues (use the one you have, but you might have to swap bells and clutch or torque conveter if you use a later block).

You have to remember that HP is a bit of an arbitrary gauge. The higher the RPM's the higher the HP generally. The reason most I-6's don't "rate" that much HP is they don't wind up that high, but how often will you really be hitting 6-k on the street anyway?
You may only see 200 HP or so, but the more important value for most street applications is torque. These engines, set-up correctly, should give you a nice broad torque curve in the 250 to 300 ft.lbs range.

For comparison: a brand new Mustang V-6 is only 210 HP, and that's a 3,500 lbs car. You may not wind as high, but there is a definite weight and torque advantage. And, mileage may not get to the 25-mpg mark, but you'll at least be within range of it, depending on your driving habits.
And, depending on the condition of the existing 200 you already have in the car, you may be able to do an incremental upgrade to the existing block without having to pull it to put in a "new" block.

Just a thought mind you.

Where do you want the 200-250 HP? The engine or at the wheels?

200-250 HP at the wheels will require some serious work and either super high compression or forced air of some sort.

200-250 at the flywheel is relatively simple. A few ways I currently know of:

1) Aussie 250/2V head. This project will run you around $1200 before the cost of a new carb.

2) Offenhauser 3x1V manifold adaptor. Depending on how you acquire the parts (these are about as rare as the Aussie heads now) it can run you between $600-1200.

3) Mike's new AL Head.

4) High compression and custom manifold modifications. A few people around here have done that to good success. Just requires some work. Can run anywhere between $250-1500 depending on how much you can do yourself.

5) Turbo the stock log head. There have been a few of these as well. Can be the cheapest way to get that power if you know a good fabricator that'll work cheap and find a good deal on a turbo. Cheap set ups can use the stock exhaust manifold as it is actually relatively well suited for this application due to close proximity of the manifold to the intake. $600-1500.


I recently dyno'd my Aussie set up at 152 RWHP. My Aussie head had enlarged valves and long tube coated headers with a 4V Holley adapted to the manfold (direct mount, not a 2-4V adaptor). With normal lost, that's around 180 BHP which, when you look at things respectively, is what a stock 4V non-HIPO 65 mustang dyno's at. That's good enough for me.

I stuck a T5 (5 Speed from an 89 V-8 mustang) behind that set up and I still manage around 25-26 MPG on the highway cruising at 70 MPH with a 3.20 rear end. My best mileage was with a warmed over 6 (new cam and ignition, but otherwise stock US Head with a 1V) and a T5. I managed around 30 MPG.



By the way, congrats on your decision to "Stay Six". It's a hard row to hoe, but IMO worth it. I love surprising people with my 6. Sure, at times things would have been easier going to an 8 but I'm still here. In fact, I've recently finished all my drivetrain and suspension upgrades. Everything on my car is Full V-8 spec (Luckily 6 convertibles have the V-8 torque boxes) from transmission, steering, spindles, brakes, rear end...even down to the throttle/gas pedel set up. All I'm missing is the engine and I guess I'd have to swap my radiator out.

Phantomace,

Isn't the 250 swap a little more involved? I was under the impression that the engine is both wider and taller, requiring diferent motor mounts? Maverick mounts I believe. Hood clearance might be an issue in a 65 as well. Correct me if I'm wrong.

Thanks guys for the info. I geuss I will have to try and find one of those 2v aussies because I just don't think I could dish out 2 grand for a new head and intake. So theoritcally lets say I find and aussie head upgrade the ignition, exhaust, warm up the head a bit, put on the electric fan, and maybe even a ram air set up what numbers at the flywheel can I exspect and should I use the 3x1 carb set up or a 2 barrel?

bookworm007":2bql8bd6 said:

Thanks guys for the info. I geuss I will have to try and find one of those 2v aussies because I just don't think I could dish out 2 grand for a new head and intake. So theoritcally lets say I find and aussie head upgrade the ignition, exhaust, warm up the head a bit, put on the electric fan, and maybe even a ram air set up what numbers at the flywheel can I exspect and should I use the 3x1 carb set up or a 2 barrel?

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It really depends primarily on the details, and your own ability/knowledge.

It's true that the log head is the largest roadblock in the system, and getting away from that opens up the possibility of making more power, but without proper cam selection, CR, carburation (or FI), exhaust, and tuning, it's not going to do you a lot of good.

What I suggest for you, and for anyone who has similar questions, is to hang around here for a while (it's not like you are planning on writing a check for parts tomorrow, is it?) and read what others post. When you see someone who is getting the sort of results that you want (and people are) get information regarding their setup, understand why they went that way and why it works, and then decide if you want to use that as a template.

There are plenty of people on this site who have a lot of experience and knowledge, and are continually pushing the envelope in various directions. The idea of hopping up these engines isnt mature enough yet to have "tried and true" power combinations. However, using another members successful combination as a template for your own is a time-honored tradiation in hot rodding. It's also as close as you can get to a garuntee of success.

While your waiting why not slip a header and a better ignition in, that will keep you busy for a little while while you plan for the rest

A 65 Mustang 3-speed is probably going to have a 2.77 trans. Even if you successfully get to 1hp/ci the transmission and clutch are going to be marginal. Don't forget to figure in some upgrades there.

Also, as a daily driver I would add some decent seatbelts and maybe even some newer seats, just for the comfort and safety factor. Next on my list would be better brakes. 9" drums.....scary.