Topic: V8 Miata - The Lemony way

Our car, the Petrosexual Trashback Miata / Mazda Metro just finished its 5th race at Gingerman a couple weeks ago.  It was the first race that we've made it all the way through with no break downs, no incidents on the track, and no black flags and we ended up in 18th overall.  We also got the first ever "Seriously, WTF" trophy for the bribe that got us into B class (still only finished 8th in B).

The car is a '94 miata that had been crashed (legit sub $500 car).  We cut the top off of a geo metro and welded it to the roof, then cut up an old trash compactor for the sheet metal sides (hence the trashback name).  Judge Eric called it the "Epitome of Miata Sadness".

https://farm5.staticflickr.com/4504/37889243291_aaac312e63_b.jpg
https://farm2.staticflickr.com/1655/26576900651_c1a0ae2a41_b.jpg


So now that we seem to have the car dialed in and reliable, we naturally have this overpowering urge to do something stupid, which is where this "almost free" V8 swap comes in.  It turns out, some V8's can be had for free in a running car, which is the case with this 1991 cadillac with a 4.9 "High Technology Engine" that I found on craigslist.  Its a FWD V8 that most people seem to dyno around 170hp and under 250 lb-ft at the wheels stock and has basically zero aftermarket support.  But, it seems like some teams have had decent reliability with them at Lemons races.


https://farm5.staticflickr.com/4169/34403832580_a2d6a500d9_b.jpg

The owner had supposedly driven this for a while about 10 years ago, then parked it for a future project that never happened.  In the time it sat there, it had been filled with all kinds of garbage and the rear window had broken out providing a family of cats a winter home (for several years judging from the amount of cat shit and hair).  After airing up the tires, running some fresh gas through the lines, and shoveling the cat shit out of the front seat, it started and ran onto a trailer.  Engine: Acquired

For the transmission, it turns out that a 1998 Dodge Dakota 2wd with the 2.5L 4 cylinder has a transmission and bellhousing that will mate up perfectly to the 4.9 GM Metric pattern.  The local scrapyard charges $99 for a transmission with bellhousing.

The plan is also to swap the diff to an IRS Ford Thunderbird 8.8, which can be had for $59 at the scrap yard.  It will require new cv axles, but its a common enough swap that aftermarket custom axles are actually as cheap as miata axles.

The running stock drivetrain from the miata can all be sold, and this swap can be done for FAR less than what we'll get out of those parts.  Our team has tons of fabrication experience, so this can and will definitely happen.  The question is, how many laps until something goes wrong?  Any bets?  Will the judges like it or give us penalty laps?

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018

Re: V8 Miata - The Lemony way

Just bring a 55 gallon drum of loose spaghetti 'o's and I bet you'll get C class with zero laps!

Butt Sweat & Beers.

Re: V8 Miata - The Lemony way

In the 80's I had a Limo service.  I eventually sold all the Caddys even though they made a much better looking Limo than the Lincoln.  One of the (many) problems was the HT4100 engine.  They came in two flavors.

1.  Engine develops a big end bearing knock at idle/low rpm around 30k miles but keeps knocking away till 130k miles when it blows up.
2.  Engine is silent as can be until 60k miles at which point without any warning at all spits the rods out the side and crank on the ground.

I'm sure you'll be fine.

1990 RX7 "Mazdarita" 
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)
1964 Sunbeam Imp (IOE 2013 Sears Pointless)
1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites) (Sold -> Houston.  Gone and forgotten)

Re: V8 Miata - The Lemony way

cheseroo wrote:

In the 80's I had a Limo service.  I eventually sold all the Caddys even though they made a much better looking Limo than the Lincoln.  One of the (many) problems was the HT4100 engine.  They came in two flavors.

1.  Engine develops a big end bearing knock at idle/low rpm around 30k miles but keeps knocking away till 130k miles when it blows up.
2.  Engine is silent as can be until 60k miles at which point without any warning at all spits the rods out the side and crank on the ground.

I'm sure you'll be fine.


So you're telling me there's a chance for success??

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018

Re: V8 Miata - The Lemony way

egesledder wrote:
cheseroo wrote:

In the 80's I had a Limo service.  I eventually sold all the Caddys even though they made a much better looking Limo than the Lincoln.  One of the (many) problems was the HT4100 engine.  They came in two flavors.

1.  Engine develops a big end bearing knock at idle/low rpm around 30k miles but keeps knocking away till 130k miles when it blows up.
2.  Engine is silent as can be until 60k miles at which point without any warning at all spits the rods out the side and crank on the ground.

I'm sure you'll be fine.


So you're telling me there's a chance for success??

Which of those two options is success?  The answer is of course, highly unlikely but always a chance.

Re: V8 Miata - The Lemony way

OnkelUdo wrote:
egesledder wrote:
cheseroo wrote:

In the 80's I had a Limo service.  I eventually sold all the Caddys even though they made a much better looking Limo than the Lincoln.  One of the (many) problems was the HT4100 engine.  They came in two flavors.

1.  Engine develops a big end bearing knock at idle/low rpm around 30k miles but keeps knocking away till 130k miles when it blows up.
2.  Engine is silent as can be until 60k miles at which point without any warning at all spits the rods out the side and crank on the ground.

I'm sure you'll be fine.


So you're telling me there's a chance for success??

Which of those two options is success?  The answer is of course, highly unlikely but always a chance.

never tell him the odds!

1992 Saturn SL2 (retired) - Elmo's Revenge -  Class B winner, Heroic Fix winner x2
1969 Rover P6B 3500S - Super G-Rover - I.O.E Winner, Class C Winner
1996 Saturn SW2 - Elmo's Revenge (reborn!)
1974 AMC Javelin - Oscar's Trash heap - Organizer's Choice

Re: V8 Miata - The Lemony way

egesledder wrote:
cheseroo wrote:

In the 80's I had a Limo service.  I eventually sold all the Caddys even though they made a much better looking Limo than the Lincoln.  One of the (many) problems was the HT4100 engine.  They came in two flavors.

1.  Engine develops a big end bearing knock at idle/low rpm around 30k miles but keeps knocking away till 130k miles when it blows up.
2.  Engine is silent as can be until 60k miles at which point without any warning at all spits the rods out the side and crank on the ground.

I'm sure you'll be fine.


So you're telling me there's a chance for success??

Oh yeah, I wouldn't sweat it.

1990 RX7 "Mazdarita" 
1994 Jaguar XJ12 (Winner C-Class 2013 Sears Pointless)
1964 Sunbeam Imp (IOE 2013 Sears Pointless)
1980 Rover SD1 (I Got Screwed 2014 Return of Lemonites) (Sold -> Houston.  Gone and forgotten)

Re: V8 Miata - The Lemony way

If this swap doesn't get you into Class C I'll eat Eric Rood's hat, or at least eat Spaghetti-Os from it!

Apocalyptic Racing - Occupy Pit Lane racing
Racing the "Toylet" Toyota Celica powered by Chevrolet Ecotec.
16x Loser with the Celica. 5 times loser in other fine machines

Re: V8 Miata - The Lemony way

The tale of the Dodge gearbox bolting right up to the Cad V8 was an eye-opener. I find that absurd! What will you use for a flywheel?

#888-Hong Kong Cavaliers Benz S500: formerly known as OMG Racing #140...
Judges Choice and Regional Award winner! Chuckwalla '12, Buttonwillow '13, BFE GP '15, Miller '14 & '15, Sonoma '13,'14,'15,'17, '18. Inde '16,'17,'18. Other foolishness: Finisher of the inaugural Lemons Rally, in the black Jag.... and IOE in the Super Snipe back in '12.

Re: V8 Miata - The Lemony way

Type44 wrote:

The tale of the Dodge gearbox bolting right up to the Cad V8 was an eye-opener. I find that absurd! What will you use for a flywheel?

The story goes that AMC/Jeep used the GM 2.8 V6 (which came with the GM metric bellhousing pattern) for several vehicles in the 80's.  They then used that same pattern for their smaller 2.5L 4 cylinder so they could continue to use the same transmission setup.  In 1998, the revised 2.5L 4 cylinder that went into the new Dakota came with the AX15 5-speed manual and had the same GM metric pattern still.  Most if not all were 2WD, so its perfect for this swap.

The Ax15 built by Aisin is the same transmission used in the old Turbo Supra (R154), the 90's V6 Tacoma (R150f), mid-2000's GM (MA5), and was used behind a few Isuzu SUV's as well (AR5).  I've run one in my turbo supra motor powered '85 toyota pickup for a few years now and never had an issue, so hopefully it will hold up well.

For the flywheel, Fiero dudes have been running clutch setups on the 4.9 swaps for years.  Some people plug and re-drill Cavalier flywheels, and some companies make conversion flywheels.  We'll see what happens when the time comes.  Its kind of a safety item, so a conversion flywheel might happen.

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018

Re: V8 Miata - The Lemony way

There is good information on this the various transmission/bellhousing combos available if you search pirate 4x4

Apocalyptic Racing - Occupy Pit Lane racing
Racing the "Toylet" Toyota Celica powered by Chevrolet Ecotec.
16x Loser with the Celica. 5 times loser in other fine machines

12 (edited by TheEngineer 2017-10-24 02:08 PM)

Re: V8 Miata - The Lemony way

It's amazing what transmissions will bolt to what. I too went down the rabbit hole that led me to learn that the MA5/AR5, R154, and AX15 all share a bellhousing pattern. You'd be amazed what a 2008 Solstice trans will bolt right up to.

unrelated, anyone want to buy a 2wd AX15 sans bellhousing? Came from a dodge dakota.

Also 120% not related, I have a 2008 solstice bellhousing I don't need either.

20+ Time Loser FutilityMotorsport
Turbo Dodge Powered E36 Build
2008 Saab 9-5Aero Wagon
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13 (edited by MDG 2017-10-24 04:08 PM)

Re: V8 Miata - The Lemony way

We like racing with y'all, here's some guidance:

Presumably you have a 1.8 diff since you can finish a race. Since you'll be running 3/4/5th gears, and making the same torque as a turbo Miata, you can probably use the stock diff, at least for a while. Might save you some time and effort. Just don't get on it in 1st or 2nd gear and the diff won't see much torque.

If you choose to ignore this guidance, I have an aluminum 8.8 and some Factory Five narrow axles you may want. Lemons took all my time away from building my Audi V8 swapped Miata so I don't need 'em.

Re: V8 Miata - The Lemony way

jimmy.shearer wrote:

Just bring a 55 gallon drum of loose spaghetti 'o's and I bet you'll get C class with zero laps!

55 gallon drum is too much like a can.

Now one of those soft bag dumpster thingys.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!"
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata.

15 (edited by TeamLemon-aid 2017-10-24 06:21 PM)

Re: V8 Miata - The Lemony way

The swap sounds cool.    Any estimates on the gallons per hour you burn with the 1.8L?  How about with the V8? 

The engine swap sounds cheap (except for the time).  Do you have a big fuel cell?

I like that first picture.  wink

LemonAid - Changing kids lives one lap at a time.

16 (edited by egesledder 2017-10-24 09:14 PM)

Re: V8 Miata - The Lemony way

MDG wrote:

We like racing with y'all, here's some guidance:

Presumably you have a 1.8 diff since you can finish a race. Since you'll be running 3/4/5th gears, and making the same torque as a turbo Miata, you can probably use the stock diff, at least for a while. Might save you some time and effort. Just don't get on it in 1st or 2nd gear and the diff won't see much torque.

If you choose to ignore this guidance, I have an aluminum 8.8 and some Factory Five narrow axles you may want. Lemons took all my time away from building my Audi V8 swapped Miata so I don't need 'em.


I considered running the stock 1.8, but 4.10's are way too much for this motor/trans combo.  I'm thinking the 3.27 ratio that the 8.8's were available with is much closer to what I'd like to run.  That, and the 1.8 diff with torsen is worth some cash, so it seems more logical to upgrade to something more stout for not much more than re-gearing the miata diff would cost, and probably come out ahead with selling the miata diff.

What's the diff from?  T-bird/mustang/etc or the Explorer?  What ratio?  Does it have the limited slip?  Let's talk.

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018

Re: V8 Miata - The Lemony way

TeamLemon-aid wrote:

The swap sounds cool.    Any estimates on the gallons per hour you burn with the 1.8L?  How about with the V8? 

The engine swap sounds cheap (except for the time).  Do you have a big fuel cell?

I like that first picture.  wink



I think we were around 4 gallons per hour with the 1.8, maybe more with the fastest driver.  V8 will be more than that, probably a lot more...  Fuel cell will be within the 24 gallon limit. 

But really, you have to measure in smiles per gallon, which will be higher with the V8.

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018

Re: V8 Miata - The Lemony way

We burn about 10 gph with a 460 cubic inch engine.  In your godless commie metrified units, that's something like 7.5 liters.  The 4.9 shouldn't burn much more than 6 or 7 gph.

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Re: V8 Miata - The Lemony way

TheEngineer wrote:

It's amazing what transmissions will bolt to what. I too went down the rabbit hole that led me to learn that the MA5/AR5, R154, and AX15 all share a bellhousing pattern. You'd be amazed what a 2008 Solstice trans will bolt right up to.

unrelated, anyone want to buy a 2wd AX15 sans bellhousing? Came from a dodge dakota.

Also 120% not related, I have a 2008 solstice bellhousing I don't need either.

What do you want for the Solstice bellhousing?

I use Chevy Colorado transmissions with solstice bell housing to connect to my LE5 Ecotec mostly because Colorado transmissions don't have sports car tax applied.

Apocalyptic Racing - Occupy Pit Lane racing
Racing the "Toylet" Toyota Celica powered by Chevrolet Ecotec.
16x Loser with the Celica. 5 times loser in other fine machines

Re: V8 Miata - The Lemony way

Brett85p wrote:
TheEngineer wrote:

It's amazing what transmissions will bolt to what. I too went down the rabbit hole that led me to learn that the MA5/AR5, R154, and AX15 all share a bellhousing pattern. You'd be amazed what a 2008 Solstice trans will bolt right up to.

unrelated, anyone want to buy a 2wd AX15 sans bellhousing? Came from a dodge dakota.

Also 120% not related, I have a 2008 solstice bellhousing I don't need either.

What do you want for the Solstice bellhousing?

I use Chevy Colorado transmissions with solstice bell housing to connect to my LE5 Ecotec mostly because Colorado transmissions don't have sports car tax applied.

Pay shipping? Shoot me an email and we can work it out. Right now it's just sitting in my garage taking up space.

20+ Time Loser FutilityMotorsport
Turbo Dodge Powered E36 Build
2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

Re: V8 Miata - The Lemony way

I have a 4.9 that I pulled out of my 1993 STS back in the day. You can have it if you want it for a spare. It had about 120000 miles on it. I can haul it to Gingerman next year...we will carry it under our giant umbrella(canopy).

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Re: V8 Miata - The Lemony way

PM sent.

TheEngineer wrote:
Brett85p wrote:
TheEngineer wrote:

It's amazing what transmissions will bolt to what. I too went down the rabbit hole that led me to learn that the MA5/AR5, R154, and AX15 all share a bellhousing pattern. You'd be amazed what a 2008 Solstice trans will bolt right up to.

unrelated, anyone want to buy a 2wd AX15 sans bellhousing? Came from a dodge dakota.

Also 120% not related, I have a 2008 solstice bellhousing I don't need either.

What do you want for the Solstice bellhousing?

I use Chevy Colorado transmissions with solstice bell housing to connect to my LE5 Ecotec mostly because Colorado transmissions don't have sports car tax applied.

Pay shipping? Shoot me an email and we can work it out. Right now it's just sitting in my garage taking up space.

Apocalyptic Racing - Occupy Pit Lane racing
Racing the "Toylet" Toyota Celica powered by Chevrolet Ecotec.
16x Loser with the Celica. 5 times loser in other fine machines

Re: V8 Miata - The Lemony way

https://media.giphy.com/media/pu6PQqp3OA1xu/giphy.gif

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

Re: V8 Miata - The Lemony way

Was just poking around on engine specs for those and wondering about weight differences when I noticed that the HT Series had aluminum blocks and iron heads. Is...Is that a thing? Why wouldn't they just use aluminum heads, too?

Yes, this is Malaise Era GM so the reason is generally "they saved a small amount of money." That said, is there any inherent engineering advantage to this?

This is all a roundabout way of saying "This is a fantastic swap idea and I'm excited to see Lemons' first V8 Miata done the right wrong way.

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

25 (edited by egesledder 2017-10-27 01:07 PM)

Re: V8 Miata - The Lemony way

therood wrote:

Was just poking around on engine specs for those and wondering about weight differences when I noticed that the HT Series had aluminum blocks and iron heads. Is...Is that a thing? Why wouldn't they just use aluminum heads, too?

Yes, this is Malaise Era GM so the reason is generally "they saved a small amount of money." That said, is there any inherent engineering advantage to this?

This is all a roundabout way of saying "This is a fantastic swap idea and I'm excited to see Lemons' first V8 Miata done the right wrong way.


Yea, no idea why they put iron heads on it.  I'm sure saving money had something to do with it.  The interesting thing is, headgasket failures are actually pretty rare on these motors for some reason.  The block with its seperate iron cylinder sleeves doesn't look all that stout or like a great idea, but we'll see how it does.

Weight wise, it will probably be under 150lbs more than the miata motor/trans setup, from my calculations.

Petrosexual Racing - 4.9 HT swap/Trashback Miata
https://forums.24hoursoflemons.com/view … p?id=35746
"Seriously, WTF Award" - 2017 - Spaghettio Bribe
BFE GP 1st in C - 2018