i have some build questions.... | Page 2 | Ford Explorer Forums - Serious Explorations

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i have some build questions....

I can't resist chiming in when forced induction's involved, it's my thing and I do have references. I actually have a T-Shirt embroidered, not printed, but embroidered that reads: "Drop compression and boost the hell out of motor".

May I suggest an article written in layman's terms just for starters? It's only 12 pages, but it runs through the basics.

http://www.holley.com/data/TechService/Technical/Supercharger%20Tech%20Info.pdf

Thats a great saying when your in a light car or a full forged built motor.but to me in a heavy ass truck and where forged kits are ridicously expensive,it doesnt seam practical.maybe in a race truck/ranger.
 



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yes, I personally don't feel great about running the 10:1 comp when boosting. Here in az the highest octane is 91 unless u go to the specialty places that have 93 and racing fuels.... I want to get rid of these 90tm heads. So i need to either just live with going with a just top end swap, hope that a good tune and 91 octane is enough for 7-10lbs and 10:1 comp, or completely rebuild engine for boost :D or at least pull my rods/pistons while engine is truck and the lower compression.... As for turbos... whats the smallest turbo i can run that can still get that 7-10 lbs on this big motor... Don't want to burn stress the turbo to much but the quicker i get the boost the better heh. What you say Rusty 7-10lb or 15-18 heh.

You do realize you would end up with the same thing,10;1 with 7-10lbs or 8:1 with 15-18lbs.but you run 15-18 your need all forged and head studs and your be dragn ass till booet builds and these arent high reving motors.if you dont feel safe at 10:1 then just stick with stock 9:1 and do cams and head work,ps 10:1 is not high at all,the sohc is 9.8:1 and people boost the hell out of it,what is low though is 8:1!! But again like i said i dont know alot about turbos or boostn
 






heh i would only do 15-18 with complete forged rebuild was mostly jking about it :P. but yea regardless of how u get HP with the boost/comp ratio its all about where u want ur power in power-band and not having detonation. hmm idk couple guys on here with their junkyard turbo builds are pushing 12-15 on stock motors with higher miles don't see why i cant run 7 and 1 more comp :/ i guess. Oh btw are these the same 95tm heads you found earlier that came with a 3 angle valve job?

thx again jd
 






heh i would only do 15-18 with complete forged rebuild was mostly jking about it :P. but yea regardless of how u get HP with the boost/comp ratio its all about where u want ur power in power-band and not having detonation. hmm idk couple guys on here with their junkyard turbo builds are pushing 12-15 on stock motors with higher miles don't see why i cant run 7 and 1 more comp :/ i guess. Oh btw are these the same 95tm heads you found earlier that came with a 3 angle valve job?

thx again jd

Who runs that much boost on a junk yard build?ive never seen anyone run over 12+ on a stock bottom end.dont get me wrong not trying to convenience you to use either head,like i said i dont know much about FI.being your in a hot area you may wanna stay at stock levels.either way i wouldnt use a 90 tm head,i would go with a 93tm head from engine quest(EQ).search "new 95tm heads.." a link will come up for the heads.yea they come with a valve job and flow out the box more than a stock head.i may know someone that is going to be upgrading from a 410 and 93tm head to a 422& 95tm so he might be selling his heads and cam,you would want a 422 cam though but the head is a EQ 93tm.i would be more worried about tuning than anything,witch our first gens have very little capability.
Ps ill be running m90 9-10psi with 10.6:1 compression,full boost and power off the line;)
 






Great discussion.

I've read the responses, but I'm gonna need at least a week to respond coherently. I started to, but it started getting waaaay tooo looong and can't finish my answer in one measly sorry-arsed post. so I'm not going to respond with short answers and vague responses. I need a little time, but let me retort. With that said....

In the meantime:

Thats a great saying when your in a light car or a full forged built motor.but to me in a heavy ass truck and where forged kits are ridicously expensive,it doesnt seam practical.maybe in a race truck/ranger.

This is absolutely right.

You do realize you would end up with the same thing,10;1 with 7-10lbs or 8:1 with 15-18lbs.

Right again

Who runs that much boost on a junk yard build?ive never seen anyone run over 12+ on a stock bottom end

Me neither, well not for long.

heh i would only do 15-18 with complete forged rebuild was mostly jking about it

I'm glad to hear you say that.


More to come....
 






Ok I'll bite-- How much HP does one expect to gain if you put on the 95tm heads and a 410 cam? I have a spare 4.0 out of a '94 and a junker '95 to rob parts off of. (The '95 would have the 95tm heads correct?)
 






Ok I'll bite-- How much HP does one expect to gain if you put on the 95tm heads and a 410 cam? I have a spare 4.0 out of a '94 and a junker '95 to rob parts off of. (The '95 would have the 95tm heads correct?)

15-20hp from the cam and a 10% increase of the overall hp, from the head.so if you made a 100hp with cam and stock heads,then switched to 95tm you would can 10hp.throw a 422 cam instead and gains are much better,they work better together. You could see 25-30ish from cam and 15% from 95tm(50-60hp gain to the ground) but even at that your only be around 180-200hp but the tq is the real gain,not hp
 






Rainbow Sherbet

You do realize you would end up with the same thing,10;1 with 7-10lbs or 8:1 with 15-18lbs.

I understand playing with Crank, Rods, Pistons, heads, can give you different stroke or compression ratio's. I made no reference of boost pressure, application, or hardware when I quoted "lower compression boost the heck out of it"; stubbornly, I will still stand by this statement.

but you run 15-18 your need all forged and head studs and your be dragn ass till booet builds and these arent high

True, hear me out........

Assumptions:

Application: Streetable, and off roading/wheeling. Driven at speeds
under 4,500 rpm and will infrequently see higher RPM's
Induction device: Roots Blower - M90 or small equivalent. (Nota centrifugal and not referring to a turbo)
Intercooler: none
Rods: Cast-stock
pistons: Cast-stock
Crank: Cast-stock
Heads: 95tm stock mostly, 3 angle valve job- mild porting
Cam: 422 - Low end torque? Correct me if I'm wrong.
Fuel: 93 pump fuel
Main Caps: two bolt -stock


The Why?:

Knowing that you're building a motor for forced induction- roots blower system. Having that info up front is valuable if you're doing a power adder purpose built motor. I don't know why anyone, given the choice, would build it with a high static compression ratio. Given the scenario above, I would build it with the7.5>8:1 Compression ratio. If anyone would know to do that cost effectively, I'll bet you would, but I have not researched it.
It is fairly easy to change the boost to get the ideal combination of performance and power by changing pulley's. Unless you disassemble, how are you to easily lower static compression ratio?
You will make greater total power with a low compression, high boost engine than you will with a high compression, low boost engine. Remember even at idle you are boosting even when a vaccuum/boost guage says "0". , and At very low engine speeds the smaller blowers will produce more low RPM torque than at higher speeds. Sound like a pretty good application for wheeling? All the power's delivered in torque, not by higher RPM's



If you dont feel safe at 10:1 then just stick with stock 9:1 and do cams and head work,ps 10:1 is not high at all,the sohc is 9.8:1

This is absolutely right. If you can't get the boost through the heads and past the valves, what good is it? Heads, according to JD4242, are one of the biggest weakness.

ipeople boost the hell out of it,what is low though is 8:1!! But again like i said i dont know alot about turbos or boostn

Turbo's are a whole other discussion. Best power adder by far, but I'm focusing on the roots blower.

Thats a great saying when your in a light car or a full forged built motor.but to me in a heavy ass truck and where forged kits are ridicously expensive,it doesnt seam practical.maybe in a race truck/ranger.

I totally agree with this. The hardware, custom fabrication, lack of affordable aftermarket go-fast goodies, and without an easily modifiable Fuel/Ignition system, it makes this build especially difficult, but I'd still do it given the opportunity.

hmm idk couple guys on here with their junkyard turbo builds are pushing 12-15 on stock motors

Not for long they aren't. I'll believe 'em when me crap turns purple and smells like rainbow sherbet. :crazy: (This is gonna generate some hate reply's)



Conclusion:

Run low boost pressure of 3 to 5 pounds. 5 at the most. There's way more to this discussion, I'm merely simplifying. The good thing is with a roots blower that you're not spinning this engine to the moon, all your additional HP is delivered in TQ.
 






I understand playing with Crank, Rods, Pistons, heads, can give you different stroke or compression ratio's. I made no reference of boost pressure, application, or hardware when I quoted "lower compression boost the heck out of it"; stubbornly, I will still stand by this statement.



True, hear me out........

Assumptions:

Application: Streetable, and off roading/wheeling. Driven at speeds
under 4,500 rpm and will infrequently see higher RPM's
Induction device: Roots Blower - M90 or small equivalent. (Nota centrifugal and not referring to a turbo)
Intercooler: none
Rods: Cast-stock
pistons: Cast-stock
Crank: Cast-stock
Heads: 95tm stock mostly, 3 angle valve job- mild porting
Cam: 422 - Low end torque? Correct me if I'm wrong.
Fuel: 93 pump fuel
Main Caps: two bolt -stock


The Why?:

Knowing that you're building a motor for forced induction- roots blower system. Having that info up front is valuable if you're doing a power adder purpose built motor. I don't know why anyone, given the choice, would build it with a high static compression ratio. Given the scenario above, I would build it with the7.5>8:1 Compression ratio. If anyone would know to do that cost effectively, I'll bet you would, but I have not researched it.
It is fairly easy to change the boost to get the ideal combination of performance and power by changing pulley's. Unless you disassemble, how are you to easily lower static compression ratio?
You will make greater total power with a low compression, high boost engine than you will with a high compression, low boost engine. Remember even at idle you are boosting even when a vaccuum/boost guage says "0". , and At very low engine speeds the smaller blowers will produce more low RPM torque than at higher speeds. Sound like a pretty good application for wheeling? All the power's delivered in torque, not by higher RPM's





This is absolutely right. If you can't get the boost through the heads and past the valves, what good is it? Heads, according to JD4242, are one of the biggest weakness.



Turbo's are a whole other discussion. Best power adder by far, but I'm focusing on the roots blower.



I totally agree with this. The hardware, custom fabrication, lack of affordable aftermarket go-fast goodies, and without an easily modifiable Fuel/Ignition system, it makes this build especially difficult, but I'd still do it given the opportunity.



Not for long they aren't. I'll believe 'em when me crap turns purple and smells like rainbow sherbet. :crazy: (This is gonna generate some hate reply's)



Conclusion:

Run low boost pressure of 3 to 5 pounds. 5 at the most. There's way more to this discussion, I'm merely simplifying. The good thing is with a roots blower that you're not spinning this engine to the moon, all your additional HP is delivered in TQ.

I agree with everything you said but the engine compression,this seems to be debated ALOT and so many things do effect it,personally if you can tune and plan to stay low in boost then it seems to be personal choice.me i built my motor for nos so im not going back to just change compression and if i do full on forge will go back in.yes the valve size is what kills the 4.0 .compare the 5.0 valve size to the 4.0 both use similar bore/stroke.for the record my bottom end is not completely stock,the crank is the only stock thing,piston and rods are aftermarket but not top grade and i have a full gurdle with arp head bolts not studs.nothing on top end is stock.the whlle motor has been blueprinted and balanced. i plan to run about 3-5psi DD and 9-10psi off road,yes im pushing it with my compression. Ps i run an intercooler
 






For anyone wanting to know how to lower there compression you would use 2nd gen ohv piston and first gen heads (93tm) that would give you 8:1
 






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