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Discussion Starter #1
Looking for an engine replacement for my worn out 351w. What is the max cubes I can run using the stock computer and speed density? I'm looking to replace with a a crate engine of some sort?
 

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I'm guessing this will be a big, fat, sloppy "no". :)
 

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I'm guessing this will be a big, fat, sloppy "no". :)
Why do you say that? I've already tracked down a 393 stroker replacement for a reasonable price. I just want to make sure I get the cam correct for the SD to handle. Somebody mentioned an RV cam.
 

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stroker means extra displaceemnt. but with stock heads, intake, cam its gonig to be pretty bottlenecked as now your trying to flow even more through a restrictive part. you will probably make more troque but not much horsepower. basicly jsut shifting the torque curve closer to idle. with stock injectors you wont be able to make too much power anyways. best bet is to stay with a stock engine. especially if you don know anything about the internals of the engine.
 

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Don't recall exactly who, but there are couple of guys on the site that have pushed the cubic inch limit with the factory EEC on a speed density set..not sure whether they were strokers or not. Having said that, if it were me, I'd save myself the headache and convert to MAF then just get a tune to run that stroker..long run I think you'll be much happier.
 

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Discussion Starter #6 (Edited)
stroker means extra displaceemnt. but with stock heads, intake, cam its gonig to be pretty bottlenecked as now your trying to flow even more through a restrictive part. you will probably make more troque but not much horsepower. basicly jsut shifting the torque curve closer to idle. with stock injectors you wont be able to make too much power anyways. best bet is to stay with a stock engine. especially if you don know anything about the internals of the engine.
I'm really just looking for an answer to my question. Being that I built a 1000hp TT for my Z06 and just recently completed a roller a 400+hp 306cid AFR Heads and Cam setup on my 66' Mustang I'm familiar with hp as a calculation of tq x rpm and engine internals.

However I haven't worked on an SD Bronco yet. I find it ironic that I had to switch over to HP Tuners 3bar tuning for my TT Vette to manage 18# boost because the MAF couldn't handle it. Now I need to switch to a MAF to run a 408cid lol. So my question for the gearheads who have swapped in a stroker in place of their stock 351w, the 94-97 Broncos is for those who have ran stock speed density setups with a 393cid.

But you have me thinking now that perhaps a stock HO 351w and replacing the front and rear gear with lower ratio would be better. The current 351w with 35" tires is a dog taking off and towing a small fishing boat. I was thinking stroker because of more low end tq.
 

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Don't recall exactly who, but there are couple of guys on the site that have pushed the cubic inch limit with the factory EEC on a speed density set..not sure whether they were strokers or not. Having said that, if it were me, I'd save myself the headache and convert to MAF then just get a tune to run that stroker..long run I think you'll be much happier.
I'm not completely opposed to swapping to a MAF, this is my son's Bronco and I was just thinking about options if I have to take the motor out I might as well replace it with something better. I also considered replacing with a stock 351w and adding some 4.56:1 gears to help propel it because it is a dog with 35" tires. I figured the extra tq from a stroker would help on the bottom. So perhaps a high output 351w with front and rear gear changes would be a better option, or less work.
 

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my point was being that theres not much reason in going a stroker. i would put that money more towards other stuff. the heads, cam, intake are already a bad bottleneck, why make them even more of a bottleneck? put the money into other stuff and yuor better off. otherwise you gonna be an engine like my 96 that has alot of displacement but is restricted by everything else. will make great torque off idle but will have no power anywhere else. basicly just shifting al lthe torque curve to be at idle. i had a 425ci stroker, AFR185 heads, 35-514-8 cam, Trickflow R intake. pretty moterate stuff and it was still a big bottleneck with such high displacement. my next build is gonig to be a 408 with AFR205, custom cam, Box R intake. it should make some real power.

now if you want to get into tuning then you defiantly have posibilities. 19lb injectors at 85% can only support around 260hp. so with tuning you can go bigger injectors. also you can tune SD but you dont want too crazy of a cam or tuning it will be really hard to get right. so if you want to do tuning then go ahread and build a moderate engine. but i would still go with decent heads and intake before going stroker. but without tuning your going to be very limited.

i would defiantly regear. this is kinda a lesson i learned between my 2 trucks. my 96 bronco with its 425ci low end torque build vs my 90 F250 302 with its mid rpm build. the 425 was built to have a ton of low end torque. while the 302 is stock bottom with mild cam and heads but higher axle ratio. the F250 definatly is my perfered vehicle. very fun to drive, pretty efficient and can tow my 88 bronco decently. i am definitly one that now likes to overgear everything. if you have an overdrive trans, put some more gear in. for 35s and E4OD i personally would like to have 4.88-5.13.
 

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my point was being that theres not much reason in going a stroker. i would put that money more towards other stuff. the heads, cam, intake are already a bad bottleneck, why make them even more of a bottleneck? put the money into other stuff and yuor better off. otherwise you gonna be an engine like my 96 that has alot of displacement but is restricted by everything else. will make great torque off idle but will have no power anywhere else. basicly just shifting al lthe torque curve to be at idle. i had a 425ci stroker, AFR185 heads, 35-514-8 cam, Trickflow R intake. pretty moterate stuff and it was still a big bottleneck with such high displacement. my next build is gonig to be a 408 with AFR205, custom cam, Box R intake. it should make some real power.

now if you want to get into tuning then you defiantly have posibilities. 19lb injectors at 85% can only support around 260hp. so with tuning you can go bigger injectors. also you can tune SD but you dont want too crazy of a cam or tuning it will be really hard to get right. so if you want to do tuning then go ahread and build a moderate engine. but i would still go with decent heads and intake before going stroker. but without tuning your going to be very limited.

i would defiantly regear. this is kinda a lesson i learned between my 2 trucks. my 96 bronco with its 425ci low end torque build vs my 90 F250 302 with its mid rpm build. the 425 was built to have a ton of low end torque. while the 302 is stock bottom with mild cam and heads but higher axle ratio. the F250 definatly is my perfered vehicle. very fun to drive, pretty efficient and can tow my 88 bronco decently. i am definitly one that now likes to overgear everything. if you have an overdrive trans, put some more gear in. for 35s and E4OD i personally would like to have 4.88-5.13.
Now that's type of info that I like to get...sometimes when we are around on forums (me not so much on this one but on many other for 10+ years) we get tired of downloading all of the good info we retain...and need to be prodded a tad :)

Your 408 AFR build sounds perfect and is right up my alley...but for my 18 year old not so much, in fact I'm hoping he doesn't read this post. lol.

I think your advice to go with a pumped up 351w with lower gear ratio is the right setup for him. If I go with some better flowing aluminum heads, maybe and RV cam for low-mid range? Does the TrickFlow R intake bolt up and work with all stock TB cables and such? If the 19lb stock injectors are only good for 260 bhp, I'm thinking I probably need some 24lb injectors to support 300 bhp. I was thinking 4.88 gears too would get up and go off idle and have some ability to pass a little bit better when needed. I'm going to suggest he switch to 33" tires anyway. Lastly any recommendations on a flash tuner or eprom mail tune?

Thanks!
 

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When buying my bronco I specifically avoided the SD broncos due to the low ability to support modified engines. However, I've read a couple engine builds since I joined that suggest I underestimated the speed density system.

Even so, there's no way I'd try a stroker on a SD bronco. Maybe if someone local showed me their stroker /SD system that worked... But I don't think you'll find many of those.

I would suggest looking up builds of speed density broncos and seeing what they did. A lot of members aren't here anymore, so waiting for them to tell you is an exercise in futility. go read the archives and see what you can find. Now, granted, there are some who will still overwhelm you with knowledge. But there are even more that call also tell you through the old threads. (This forum be old)
 

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my trucks are all MAF and OBDII. my 88 converted to use 96 Bronco wiring and my 90 F250 uses 96 Explorer 5.0 EFI. so i dont have experience tuning SD. but my understanding is you want to use a something like a Quarterhorse or TweecerRT that can datalog so you can fine tune as you go. its definitly not as easy as MAF. but as long as you dont have too crazy of a cam, it should be tuneable. basicly you want the vacuum signal at the MAP to easilly be able to tell what is going on. with a loppy cam or something where there low vacuum at idle, it gets really hard to tune.

24lb injectors are good for about 325hp @ 85%. so its definitely a bump. should be pretty easy to find some 24lb also as alot of mustang guys are probably looking to get rid of them to go bigger. i plan on gonig up to 24 in my 88 mud truck so i can remove that bottleneck, dont want to go bigger because if something goes wrong with the EFI, it basicly chokes you out running rich. i had 36lb injectors on it before and when the o2 sensors and MAF failed, it was unuseable. with 19lb injectors i was at least able to keep driving. so thats something of failsafe to keep in mind if theres ever an issue is not to have too big of injectors that you cant get home if a sensor fails.

the Trickflow R intake bolt so n jsut fine. but you will have to fiddle with modifying a throttle cable, changing the wiring pigtails to reach. making an intake. its a mustang style intake afterall. but i have mustang style intakes on all my trucks. extending the harness isnt soo bad. you can point the intake either left or right which is kinda cool. i use to silversolder a new bead on my theottle cables which was always a pain, now i jsut use a mustang throttle cable bracket and then weld a small extension on it so i can use the stock throttle cable. supposedly a Lightning bracket works, i tried one and it didnt for me.

i would keep the engine stock for now. regear it and see how you like it. make sure he doesnt ruin the truck too quickly. theres people on here who seen how i treated my trucks when i was that age. after a few years when hes shown to be responsible then build him an engine.
 

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I had this reasonable response saved in my favorites from an F150 board.

Conanski said:
There seems to be some misunderstanding of just what is possible with these EFI systems.
  • The MAF system is better able to adapt to mods which means it produces better results but it's still has limited adjustment range without tuning.
  • There are cams that can be used in both SD and MAF applications that will produce significant power increases without tuning, more radical cams will require tuning regardless of EFI system type.
  • Neither SD or MAF has enough adjustment range to handle a complete topend upgrade.. heads, intake, cam and exhaust all together.
  • the stock 19lb injectors can only feed about 275hp after that they have to be upgraded and that requires tuning. A cam and exhaust gets closest to this threshold for the least amount of money.
If I was going to suggest a max torque combo for a stock 5.8 it would be a cam with longtube headers into a single 2.5" exhaust system, that will produce roughly 260hp/275tq and run like a stock motor. Heads and intake with the stock F4TE cam won't deliver as good a result because the stock cam is too restrictive. If you want to go bigger than that it gets a lot more expensive very quickly as upgrades to the fuel system and the addition of a tuner to make it all cooperate will be required on top of whatever engine upgrade are made.
Lower gears, Edelbrock Truck intake and exhaust upgrades should be enough for anyone not looking for a race car.

Add a mild SD-friendly cam & GT40 heads for a bit more performance.
 

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Discussion Starter #13 (Edited)
my trucks are all MAF and OBDII. my 88 converted to use 96 Bronco wiring and my 90 F250 uses 96 Explorer 5.0 EFI. so i dont have experience tuning SD. but my understanding is you want to use a something like a Quarterhorse or TweecerRT that can datalog so you can fine tune as you go. its definitly not as easy as MAF. but as long as you dont have too crazy of a cam, it should be tuneable. basicly you want the vacuum signal at the MAP to easilly be able to tell what is going on. with a loppy cam or something where there low vacuum at idle, it gets really hard to tune.

24lb injectors are good for about 325hp @ 85%. so its definitely a bump. should be pretty easy to find some 24lb also as alot of mustang guys are probably looking to get rid of them to go bigger. i plan on gonig up to 24 in my 88 mud truck so i can remove that bottleneck, dont want to go bigger because if something goes wrong with the EFI, it basicly chokes you out running rich. i had 36lb injectors on it before and when the o2 sensors and MAF failed, it was unuseable. with 19lb injectors i was at least able to keep driving. so thats something of failsafe to keep in mind if theres ever an issue is not to have too big of injectors that you cant get home if a sensor fails.

the Trickflow R intake bolt so n jsut fine. but you will have to fiddle with modifying a throttle cable, changing the wiring pigtails to reach. making an intake. its a mustang style intake afterall. but i have mustang style intakes on all my trucks. extending the harness isnt soo bad. you can point the intake either left or right which is kinda cool. i use to silversolder a new bead on my theottle cables which was always a pain, now i jsut use a mustang throttle cable bracket and then weld a small extension on it so i can use the stock throttle cable. supposedly a Lightning bracket works, i tried one and it didnt for me.

i would keep the engine stock for now. regear it and see how you like it. make sure he doesnt ruin the truck too quickly. theres people on here who seen how i treated my trucks when i was that age. after a few years when hes shown to be responsible then build him an engine.
Sounds like a solid plan.
I had this reasonable response saved in my favorites from an F150 board.



Lower gears, Edelbrock Truck intake and exhaust upgrades should be enough for anyone not looking for a race car.

Add a mild SD-friendly cam & GT40 heads for a bit more performance.
One of the engines I found on Ebay from CREB is this exact setup. Will this motor work with the stock EFI and intake?


The only thing I can think of is dropping a single plane setup and stand alone controller, but I will have to check to see what others have done and how much work it entails.
 
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