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edizzle89
edizzle89 Dork
9/12/18 2:26 p.m.
Mustang50 said:

How much is this going to cost versus the cost of a rebuilt 4.2L truck engine?

I was going to suggest this as well, i dont know alot about 3.8 to 4.2 swaps but i know i've seen it done in mustangs and i'd imagine the 4.2 is probably cheap and a bump in displacement has never hurt anybody (besides at the pump).

KentF
KentF Reader
9/12/18 8:28 p.m.

Mustang50 and edizzle89 you are correct a rebuilt stock 4.2 would be a much lower cost option.

Some quick research on the interblag indicates that would cost roughly $2000. Further research indicates my existing 3.8 already has more power than a stock 4.2 (I estimate Mistress generates in the 230 to 240 HP range based on air flow measurements - although at the moment it makes zero power).

However, with the addition of my existing camshaft, ported intakes and replacing the damaged head with new ported one the 4.2 would absolutely make more. Extra cost about $1200 for head, gaskets, etc.

So - Total cost of a re-built stock 4.2 with the existing modifications transferred to it would come in somewhere about $3200. It might not even need a new tune ($150)! I could easily justify going this route. It makes a lot of sense!

However, one of the goals listed long ago was to move to a Pro-charger, probably of the 7 - 9# boost variety. For a robust build (I hate tow trucks) this should be combined with forged internals, low friction coatings on piston skirts and all that rot. That is part of the driver for going with a full hardened rebuild of the existing engine. The dropped valve has simply moved up the timeline (and cut my season in half). And if you are going to do all that work the data shows it should be a stroker. The stroker will put out something like 30 to 40 Ft-Lbs more torque depending on whose data you want to believe.

Cost for this rebuild - Forged parts, stroker crank, etc. about $5000. Gaskets, ARP Studs, replacement head, etc. another $2000. Machining $500. This build will cost $7500 or so. Lot of money, will require interest payments ( I hate that).

The resulting 3.8 ltr should have as much or more mid range torque as a GT of the same era (it already has about the same power) and it is lighter and better balanced. It will be fully hardened and prepared for the power adder if I ever really add that (another $6k someday).

When I write up the article on driving the friends GT with my tires it will show some interesting results with tire limited cars on an autocross course. There is a reason people are putting 13" wide rims on the back of these things.

The result is Mistress should be a robust build good for long trips in the moonlight and afternoon delights (also known as one minute arguments) on course.

That is "The Plan".  As I said many words ago - It takes a bit of madness...

KentF
KentF Reader
11/3/18 9:17 p.m.

The Madness Continues

I have been working 70 hour weeks the last three months on a horrible project from hell that has finally wrapped up. As a result, progress has been slow but now I can get my life back and put in some updates here. 

Engine has been pulled out of Mistress and torn down to the block.  I was able to pull the block with the hood still on using a rental engine jib from the local hardware/rental. I borrowed an engine stand from a friend at work and set about disassembly of the block. Parts are stored in cupboards and the trunk.

I also made a support bar to hold the transmission up while the engine is missing>

Initial inspection during disassembly indicated a large hole in piston #3 (but we knew that), aluminum shrapnel everywhere with some larger bits in the oil pan.  #3 cylinder bore looked very good with no marks or scoring. It appears the dropped valve stayed in the center for the 10 or 15 seconds the engine ran after failure. One noteworthy observation is that the cam bearings were very worn. They were not like that when that cam went in two years ago. Not sure what to think about that (comments/wisdom?). Everything else looked OK for an engine with 180k miles on it.

I made a wood frame for transport and took the block down to Manitowoc Engine Machining and Parts.  They have cleaned & inspected it, ran a magniflux check for cracks. Their measurements indicate that a minimal clean up of 0.020 overbore will be all that is necessary. Now they will hold it until the parts arrive.

This week I finally ordered new parts from Super Six Motorsports in Georgia. If you follow this log you know I have put in some favorable words about them with earlier engine mods. Tom did not disappoint as we worked through the dynamics of how this car is used (daily/long trips/heavy autocross), the RPM ranges it operates in, potential future mods (Procharger?), etc. This is what we came up with:

  • Long Rod 4.3 stroker rotating assy, Bore: 3.830" (.020" over), 9.5:1 CR, King main/rod bearings (cam bearing by the shop)
  • Piston hard coat black anodize entire piston
  • Stage 3 cylinder head omit spring/lox/retainers (replacing the old one and 12 new valves).
  • ARP head studs

This will yield a slightly higher compression ratio but still allow 93 octane pump gas (91 octane if I retard the spark a couple of degrees per my tuner at VMP). I do not know yet if I will need a new tune.

Pistons and rods are forged. This will be 4.2 displacement give or take depending on how the block is decked, gaskets and all that. Total cost is $4600 with shipping (Yes  - the madness prevails but I really miss driving this grin maker of a car).

The Block work will be about $450 and I will have them balance the rotating assembly. I have not asked but that will probably be  $150 more or such. With gaskets, etc. I will be all in for just under $6k. Part due to arrive in mid December.  I will have the shop insert the rods/pins in the pistons after balancing but I will do the assembly.

While I wait: The engine bay needs to be cleaned up, paint the rocker covers, clean all parts, strip the old paint off of the upper manifold & re-paint, etc. I plan to electro coat all/most of the exposed fasteners (Eastwood Kit on order).  Lots of little projects now that I can stand in the engine bay (with some difficulty climbing in). 

More to come…

KentF
KentF Reader
11/13/18 8:46 p.m.

Comparisons

Last August, while Mistress sat neglected in the garage with a half torn down engine I drove a friends 2000 GT at an autocross at K. I. Sawyer in Michigan's UP. 

I was planning to go up for the weekend as Safety Steward and security detail but had no ride. Ken Bartol offered to let me drive his car if I brought my own tires. Ken and his son were driving a different car and his Mustang was available. It took some convincing but I arrived on site with friends already mounting  my tires on the thing (Jeez got my own pit crew! Friends are a great thing to have. Everyone should try it!) 

Although this car is the same vintage as Mistress the two cars are very different beasties. 
Mistress is a heavily prepared car a little low on torque. The loaner is a nearly stock car showing some wear and tear and rides on a thick sticky carpet of torque. 

Mistress with the modified V6 has an automatic and 373 rear verses "Loaner" with a stock 4.6 2 valve, stick shift with 410 rear. 

Both cars had my 9" x 17" wheels and RE71R tires. Same surface, similar conditions, same crappy driver, one month apart.

Since the courses were different and to help reduce other factors (such as my not having driven stick in several years) I decided to datalog and make simple comparisons between the two cars such as cornering, braking, and acceleration.

And I had a blast - thanks Ken!

So which car performed better -the stock torque monster or the prepared grocery getter? A year earlier Ken and his son drove this car at an event at Sawyer. Ken beat me and I beat his son. If I recall the three times were all withen a second or so on a 1 minute course. Very close. Since then Mistress got a new front suspension, battery relocation, gears and so on.

Acceleration: Loaner averaged about 0.5 G in 1st and all the way through 2nd. Mistress pulled about 0.6 G in 1st and 2nd - dropping off at higher speeds in 2nd. How can that be? Both cars are tire limited and Mistress is lighter. The lower torque only became apparent as rpm got up in range. 

Put some 11" wide wheels on the back and the results would likely be reversed. 

Cornering: Loaner held in the sweepers at 1.0 G with moments at 1.1 G. Mistress sustained 1.2 G with moments at 1.3. Granted the tires were slightly newer a month earlier. One G in a full bodied car on sticky DOT tires is pretty typical.  One point two is pretty damn good. Again, Mistress is lighter, better balanced with better better geometry. And it cost thousands of dollars and hundreds of hours of work to glean that lousy 0.2 G. Still, as I detailed in an earlier post this can add up to a second or so on a one minute run.

Braking: No test. Loaner had the anti-locks turned off and I believe the rear calipers were sticky from sitting much of the past year (it's a Ford thing). Rear brakes were weak and I could not control the fronts until later runs. I looked terrible out there (or entertaining depending on your perspective) and I think I flat spotted a tire. Unfamiliar car, bad driver, no test.

Take away: By the numbers the highly prepared grocery getter should be the faster car on course. But not so much that a better driver in the GT could not easily catch it. Fatter tires would equalize acceleration but that advantage might be reversed on cornering. 

Then again, Mistress is much easier to drive well. Throttle and brakes are much more forgiving. Less sway and predictable "planted" feel. The GT is a wild tail wagging son of a beast. 

I guess that is why I had so much fun driving it! What a kick! Thanks again Ken!

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