Hi im new here. Looking for some tech advice on an engine build up im going to start gathering parts for over the winter. So im looking into to purchasing a nice shortblock. I been doing alot of research. I'm very interested in the modular boss block for the extra displacement. Im aware of the the main cap problems with this block and rgr has some nice custom main caps available through JPC. Im not very family with all the technicalities with engine internals. Im interested with this block and maybe a destroker crank making 288 ci or stock stroke crank. I definitle am shooting for the new tfs 4.6 heads. I also want to run a either a twin screw or a single turbo setup. Should i be aiming for the 44cc heads or the 38cc with a dished piston. im not planning on running a ton of boost maybe 10-14psi. I like the idea of a high reving destroker engine. Havent seen it done on any 2valve in my area. But would the stock stroke be better? Would a turbo or twin screw work better with the destroked engine??? Would the 4.6 victor jr intake work well with the turbo or should i save for a sheetmetal intake like logan motorsports. Any help or advice you can provide is greatly appreciated. Thanks
Engine Build Advice Please Help
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wmburns
SN Certified Technician
Goals?
IMO, you should list your goals for the project. Are you trying to make a fast street car, Street/strip car, all out track car?
Straight line or road course?
Budget build, mid level, or $$ no object?
Horse power level? 400, 500, 600, 700, 800.....
NA or boosted (boosted I assume).
Are you doing the work yourself? If so, level of ability? For example, good but would perfer a kit (already worked out. Just install).
Again, IMO, too many people start projects without really understanding what it is they want to do. Start with a rough set of goals. Plan from there.
It's exciting. Good luck.
IMO, you should list your goals for the project. Are you trying to make a fast street car, Street/strip car, all out track car?
Straight line or road course?
Budget build, mid level, or $$ no object?
Horse power level? 400, 500, 600, 700, 800.....
NA or boosted (boosted I assume).
Are you doing the work yourself? If so, level of ability? For example, good but would perfer a kit (already worked out. Just install).
Again, IMO, too many people start projects without really understanding what it is they want to do. Start with a rough set of goals. Plan from there.
It's exciting. Good luck.
patman0911
Founding Member
Yeah, a clear set of goals for the car would help narrow down your options.
Some of your ideas seem to be at odds with each other - a turbo or blower kind of negates the need for a destroked, ultra high rpm turner. How high do you you want to spin it anyway that your thinking about destroking? Stock cobra stuff already goes to at least 7K and there are cars going up to 8500 without destroking - I think there's a 5.4 or two spinning that fast too and they've got an even longer stroke.
Somewhere from deep in the recesses of my mind, I'm recalling reading that for an engine of equal overall displacement, turbos like a longer stroke - better exaust flow and temp characteristics to spool them up faster and at lower rpm. There's probably a lot more important considerations before the effect of bore vs stroke is worth worrying about though unless this is a race engine and you're trying to eke out ever fraction of a horsepower within a class rulebook.
edit: one more thought...
I think a centrifugal blower or turbo will be better suited for high-rpm (beyond stock RPM ranges) use than a twin-screw or other positive displacement, but you'll sacrifice low-RPM boost and/or suffer turbo lag. However, you're talking about levels way past the 400~500HP range where it seems to be fairly easy to get to whichever route you take.
Some of your ideas seem to be at odds with each other - a turbo or blower kind of negates the need for a destroked, ultra high rpm turner. How high do you you want to spin it anyway that your thinking about destroking? Stock cobra stuff already goes to at least 7K and there are cars going up to 8500 without destroking - I think there's a 5.4 or two spinning that fast too and they've got an even longer stroke.
Somewhere from deep in the recesses of my mind, I'm recalling reading that for an engine of equal overall displacement, turbos like a longer stroke - better exaust flow and temp characteristics to spool them up faster and at lower rpm. There's probably a lot more important considerations before the effect of bore vs stroke is worth worrying about though unless this is a race engine and you're trying to eke out ever fraction of a horsepower within a class rulebook.
edit: one more thought...
I think a centrifugal blower or turbo will be better suited for high-rpm (beyond stock RPM ranges) use than a twin-screw or other positive displacement, but you'll sacrifice low-RPM boost and/or suffer turbo lag. However, you're talking about levels way past the 400~500HP range where it seems to be fairly easy to get to whichever route you take.
trinity_gt
10 Year Member
That block sure looks nice and with a relatively big bore, it should help a good set of heads flow by unshrouding the valves. For a street engine with moderate boost, I don't think you should have to worry about the main caps.
Good article:
FRPP Boss 5.0 Block - Cast-Iron Modular Block - 5.0 Mustangs & Super Fords Magazine
As for destroking, perhaps it's just me but I don't see the need for this. At 3.54" the modular stroke is already fairly small -- the engine only displaces 281 cubes as it is! -- and 4V variants with steel cranks come from the factory with 7000RPM redlines. I think you could easily hit your RPM desires with a decent bottom end on a stock stroke. It just seems that even with F/I, the engine is already displacement-challenged. Cutting that back for the perceived benefit of more RPM seems wrong, especially when you can build a high-RPM street motor with the stock stroke.
Choose your components to get a compression ratio commensurate with your expected boost level and fuel quality. I'd hazard a guess at an 8.5:1 ratio for pump gas but maybe the TFS heads allow more static compression before detonation.
As I said above, I don't see the benefit of taking displacement out of an already small engine to get more RPM, especially when 7000+ RPM motor can be built with stock stroke dimensions.
If you must destroke for more RPM, I would think a turbo would be more amenable overall. A KB twinscrew might have a maximum RPM limit of, say, 18000RPM. If you want to spin the motor to 8000RPM, you might be limited in your pulley selections to limit the blower speed which can result in soggy bottom end performance. A turbo would have no such limits. A turbo might like the exhaust energy of a longer-stroke but the effect would probably be negligible.
If you really want to spin the piss out of the engine, you'll want to stay away from the long-runner style manifolds (e.g. stock PI or like manifolds...) But a short-stroke engine is going to be torque-challenged off-boost and you'll really notice that with a short-runner sheetmetal unit. To choose your combo, you need to assess what it is you want to do with the engine, how it will be used, how big a turbo you'll run and where it will spool etc. For example, a turbo free-flowing enough to work at 7000RPM might be a little laggy around town. If you have a short runner intake, you might find the car a little soft across an intersection. If you'll be living at high RPM all the time, not an issue: But if you'll be daily driving the thing every day in traffic and using the RPM once in a rare while, maybe you need to re-think the combo...
wmburns
SN Certified Technician
The previous posters all make good points. This also dovetails into the advice about your goals.
Everything that follows is IMO.
I would never take the car to the track. It would be 100% street. Therefore, street drivability is a prime concern. In my mind I would easily pick torque over horse power because a high HP engine that doesn’t make big HP unless highly revved doesn’t make the best street combo. Low end grunt for me.
Further, I am not made of $$. I could never afford an all out build.
Next, I would want to do as much of the work as possible myself. Therefore, I would pick a reliable power adder kit where the engineering work has already been done.
For me, that would be the Kenne Bell supercharger. The KB kits are well engineered. A proven design. Make tons of low end torque.
With regards to your choice of block. Great idea!
However, I would not de-stroke it. I might consider an over bore but that is all. Again, back to my goals. A reliable street engine. Excessive over boring and stroking tend to reduce reliability.
Regarding your choice of heads. Since my goal is a street motor running on pump gas, the lower compression ratio is better (boosted application). Also consider that in a boosted application, the advantage of high flowing heads is somewhat reduced verses stock heads (boosted verses NA). Again, if $$ is no object, go for the best. If trying to stay with a budget, stock heads may fit the bill.
Again, the choice of heads also depends upon your HP/torque goals. If your goal is to make 500 street HP, Stock heads will work. If your goal is 1000 HP, then every imaginable method to increase flow will have to be considered.
Consider reading Sean Hyland’s book “How To Build Max-Performance 4.6-Liter Ford Engines”.
Amazon.com: How To Build Max-Performance 4.6-Liter Ford Engines (Cartech) (9781932494686): Sean Hyland: Books
For me, I believe in the KISS theory. In that regard, I would tend to use a combination that met my goals but was already proven. I would not want my project (and $$'s) to be on the “bleeding edge”.
If you want real world examples of what happens when parts are assembled without a plan, just look at the "for sale" ads in the forums. Lots of nice parts without a home. Projects started with unrealistic goals and/or not enough $$.
I hope you can see how the choices should fit the design goals. In the end, this is your project (and your time and money). Good luck.
Everything that follows is IMO.
I would never take the car to the track. It would be 100% street. Therefore, street drivability is a prime concern. In my mind I would easily pick torque over horse power because a high HP engine that doesn’t make big HP unless highly revved doesn’t make the best street combo. Low end grunt for me.
Further, I am not made of $$. I could never afford an all out build.
Next, I would want to do as much of the work as possible myself. Therefore, I would pick a reliable power adder kit where the engineering work has already been done.
For me, that would be the Kenne Bell supercharger. The KB kits are well engineered. A proven design. Make tons of low end torque.
With regards to your choice of block. Great idea!
However, I would not de-stroke it. I might consider an over bore but that is all. Again, back to my goals. A reliable street engine. Excessive over boring and stroking tend to reduce reliability.Regarding your choice of heads. Since my goal is a street motor running on pump gas, the lower compression ratio is better (boosted application). Also consider that in a boosted application, the advantage of high flowing heads is somewhat reduced verses stock heads (boosted verses NA). Again, if $$ is no object, go for the best. If trying to stay with a budget, stock heads may fit the bill.
Again, the choice of heads also depends upon your HP/torque goals. If your goal is to make 500 street HP, Stock heads will work. If your goal is 1000 HP, then every imaginable method to increase flow will have to be considered.
Consider reading Sean Hyland’s book “How To Build Max-Performance 4.6-Liter Ford Engines”.
Amazon.com: How To Build Max-Performance 4.6-Liter Ford Engines (Cartech) (9781932494686): Sean Hyland: Books
For me, I believe in the KISS theory. In that regard, I would tend to use a combination that met my goals but was already proven. I would not want my project (and $$'s) to be on the “bleeding edge”.
If you want real world examples of what happens when parts are assembled without a plan, just look at the "for sale" ads in the forums. Lots of nice parts without a home. Projects started with unrealistic goals and/or not enough $$.
I hope you can see how the choices should fit the design goals. In the end, this is your project (and your time and money). Good luck.
oxfordgt
Member
Like most people have said state your hp goals and it would be easier to tell you how to build. Stay away fromt that book posted above. It is full of complete garbage and wrong info.
trinity_gt
10 Year Member
oxfordgt
Member
I can't remember off hand exactly what was wrong since it has been years since I read it and laughed my ass off but there were wrong wrong specs on the engines. The specs on the blowers they had in there were way off. The engine builds were way off including how they timed the engines.
