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4.6 stroker short block

10K views 58 replies 25 participants last post by  General Zod 
#1 ·
havent been on the boards in a while, just finished up with highschool so i been pretty busy.

i recently came across a 97 30th aniversary xr7 and im planning to make it my street/strip car. as a starting point for the motor ive been looking into aftermarket 4.6 and 4.6 stroker blocks but dont know which i should go with. im leaning towards livernois, but id like to hear what other people think.

i also have another question. for the time being i plan on keeping stock heads etc but replacing the short block, would there be any modifications (ECU or otherwise) i would need to run the cougar with a new short block?

any and all input welcome, thanks.
 
#6 ·
The "Big Three"

Any internal combustion engine's power and torque curves are 90% determined by the "Big 3", Heads, Cams, Intake. If you are leaving your heads stock (where the cams are BTW), you're gonna have a hard time raising your power curve over stock just modifying the stroke. Master486 is absolutely correct here (he is most all the time anyways...:D)

Street/Strip? Port your heads (doing a PI head/cam swap on your 97) would give you the best bang. PI intake will work great for you too. If you really want to go from mild to wild, check out some aftermarket cams after you do the PI head/intake swap. Let someone qualified dial it all in for you to avoid PTV contact.

I'm sure some others here who have done mods will pipe in with something similar or maybe not...lol :zdunno:
 
#7 ·
Destroked bigbore! Someone do it!
 
#27 ·
Converter & Gears



True that. My boss has been a mechanic his whole life (he's about 40), and he owns a 302 5-speed Muskrat he says is the fastest car he's ever owned. After putting a 3.73 TL in the back, it turned into a TOTALLY different animal, no lie! The car has some really wide sneakers on it and I'll tell you, it NEEDS them.
 
#11 ·
I know some people like to bore rather than stroke. I've always loved the stroker motors. I had a mark vii with a 347 stroker. as far asthe stock heads I know I won't see an enormous power increase but it's just temporary until I save up for the heads and cams I want and I just want to know if I can do it for now.

something else I have been looking into is an svt lightning motor swap. has anybody ever done this or have any input on it. I'm not making any final decisions until I know it's the best one.

just FYI down the road inplan on running a procharger setup between 15-20lbs of boost with methanol injection. trans will be built, with what parts, I'm not sure yet either
 
#15 ·
A mod engine (stroker or not) is way to expensive to make go fast
That's a giant pile of BS right there. It's only "way too expensive" if you buy the useless crap like $200 throttle bodies, $100 TB spacers, and $200 plenums that give you absolutely no real gain. For much less than the cost of all that, you can get an entire PI intake. For just a bit over $500, you can get a set of good cams. So let's see, $750 can get you cams and an intake... or $500 can get you a throttle body, spacer, and plenum that give you nothing. Maybe a little bit from the plenum... only if you've got a centrifugal blowing through it.
It's only "way too expensive" for the people that don't think before they buy.
 
#16 ·
then there is also the fact that engine's aren't fast by themselves...they need to be attached to a car :)

in Miller's defense, I do believe he was referring to the fact that Mod motor'd cars (MN12s to be precise) are "expensive" to get fast, mainly because the user only thinks about horsepower mods.....and its true that it gets expensive quick, because a lot of newbs only focus on engine mods because they just dont know any better (or perhaps they do but dont want to spend on drivetrain mods because its their only car and they secretly want to keep their fuel economy, but don't want to say so)...keeping a stock 12" converter than can only do 5400 RPMs, a stock 3.08 or 3.27 differential will definitely make things expensive on the other side of the car: in the engine bay
 
#17 ·
campared to the lsx motors and 5.0's i would say the modulars are more expensive to mod. and the fact that the thunderbird is a tank adds to that.. :zwall:

because a lot of newbs only focus on engine mods because they just dont know any better (or perhaps they do but dont want to spend on drivetrain mods because its their only car and they secretly want to keep their fuel economy, but don't want to say so)...keeping a stock 12" converter than can only do 5400 RPMs, a stock 3.08 or 3.27 differential will definitely make things expensive on the other side of the car: in the engine bay

exactly my problem. 410 gears +stall or a blower. either way you will spend money to make the modular go.
 
#18 ·
Yes, that I can agree with. Although the gear change is fairly cheap IMO. I've focused mostly on motor mods with my car simply because I've run into deals on my parts that I'd be stupid to pass up. I have 4.10's and a Jmod but still stock converter, and my motor absolutely needs to spin past 5400 now. I'm just waiting on a good TC deal to come around whenever I have the money for it.

And miller also suggested dropping a 351W in.. and leaving it at that. So not only are you defending him... you're also describing his current thought process. :)
 
#20 ·
Although the gear change is fairly cheap IMO.
you're absolutely right...its not that expensive....probably less than $500 for gears, a rebuild kit, T-lok unit, and labor if you shop around.....and with the right gears, it can make these pigs we call mn12s accelerate a heck of a lot faster.....but notice how the 18yr old thread starter is focusing on engine stuff?....yea I emphasized his age, not because 18 is too young to know anything, but because its a common thing here on this site.....they just want to focus on bragging about having more power under the hood

the issue with gearing one of these cars properly is that to truly maximize the potential, one would need gearing far higher (numerically) than they can live with on a daily basis.....mainly because once you go 4.10+ (which is the absolute minimum these cars need to get out of their own way), you need to take into account the cost of highway fuel economy, an Xcal programmer and tune-cost, and the cost of a speedcal or similar device to correct the speedometer and signal going to the pcm, some good tires, and an upgraded driveshaft....thats an easy $1000+ cost right there that most newbs just won't (can't) spend...."all for what?", the newbs ask?......to make the damn gears work in harmony with the car they are installed in.....round and round the performance circle we go.....
 
#21 ·
I have spent around 7k on my car to get it into low 12's probaly high 11's now with the new exhaust and BKK 78mm TB I just got in the mail today :). That's all that things in my SIG. I shop around alot.
 
#22 ·
Personally, I wouldn't fool with a stroker 4.6 unless I was putting DOHC heads on it. But, for that amount of money, you could get a used 4.6 DOHC with C series heads and slap a Vortech on it, make around 430 RWHP and still spank what any N/A stroker could deliver for less money. If I had to do it all over again, I would have ditched the SOHC for a DOHC, but back in 2003 when I swapped my heads, this seemed like an easier option.

Pete
 
#24 ·
I would do Boost first biggest power adder. Then build it. Once it's built just turn up the boost :)
 
#25 ·
The problem with boost is the supporting mods like fuel pump, injectors, tune, and the little things you should do like a converter and driveshaft in order to make it safe. Things add up quick no matter what you do to these cars. It is just reality I guess.

I can honestly say though that I am 5000 into the car and parts together and running 13.1 in the quarter. Add a 125 shot of nitrous and instant 11's.
 
#26 ·
Dudes, get a used Vortech off ebay for like 1500 bucks, and a stock 4.6 32V with the C series heads doesn't need all those other add-ons to make big power. I had a friend with a 99 Cobra that was 100% stock, minus the Flowmaster catback, Vortech S trim with 6 PSI, and a good dyno tune. He made like 415 at the wheels and the car ran high 12's in Pueblo Colorado. With the low boost, he didn't frag anything because he didn't have detonation issues and he also didn't need a lot of the expensive supporting mods because the power was kept reasonable. A 4.6 with stock internals and a good tune will live for a long, long time if it has a solid tune and is fed good fuel.

Pete
 
#28 ·
A 4.6 with stock internals and a good tune will live for a long, long time if it has a solid tune and is fed good fuel.

Pete
how long is a long time? i have an npi 4.6 with cams intake, and tune with 140k miles. i want to put a blower on there but everyone is tellin me if it breaks down while in college your f*cked.. which is prob true as i dont have the money for a blower and a motor.
 
#30 ·
There were several members on this board who got over 100K on their AED kits at 6 PSI with no issues. In the time he owned that Cobra, he put 30k on it with no issues. He wound up selling the car for a Mercedes and it was still in good working order.

Pete
 
#33 ·
correct....but incorrect about me.

look at my original question, it takes a simple answer. not somebody telling me that im just like every other ignorant kid out there who just wants a fast car for bragging rights.

i ask because i want to be sure that i can do it before i go through with it, which is why i ask for evyerbodies opinion
 
#35 ·
ignorant statement or not, I've been around here long enough to see trends come and go, same with people...so my statement has its merits that you can't see

so be it...i'll be waiting for the day you prove me wrong and build up a car that can stand out here on tccoa....so you better be running 11's naturally aspirated, or low 10s with a power adder, if you're planning on standing out in our community....can't remember how many times i've said that over the years :)
 
#37 ·
Listen, GM and TGJ are both absolutely right. There has been some good advice in this thread-some you should listen to. Low 12 second/high 11 second cars are possible with stock stroke and bore with the right parts. My car is an example of this. It's easy enough to buy/build one just like it, or if the price is right, buy the complete powertrain already setup and ready to go. Everything is for sale-you just have to offer the right amount of money.
JL
 
#42 ·
Not being overly familiar with modding a 4.6 but I'll give my input.

If you start with the engine your asking for failure--ask the man about to put a 3rd tranny in the SC (Stock, stock rebuild and 3rd will be a DD/SF combo). Start with gears then tranny then engine. That is unless you plan on stay under a 100hp over stock.
 
#46 ·
I know I should probably know this if I am gunna be on this forrum, but I am wondering what the stock HP for a 4.6l 96 thunderbird lx is? I know I will probably get some cocky responses but hey, give me a break I just got the car and am trying to determine the value of modding the car.
 
#50 ·
I have 2 different brand new never fired big bore 2V motors I'd sell you. Both have nothing but the best in them. Can be PI heads or SVO, have a set of each set up for big bores. Both would easily run 11s in an MN12 car, 10s in something lighter, no blower needed.

Or a fully dressed 03 Cobra motor for that matter too if you want to go that route.


I'm getting out of 4.6 stuff and switching to Coyote, so I have a lot of stuff here. All first rate stuff and I know what it is, so not something you are going to buy for next to nothing.
 
#53 ·
I was wondering what ever happened with your Big Bores. I might have to make another trip down to Texas sooner than later...
 
#52 ·
Hey, it's all for sale. Cars, motors, anything. :D
 
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