Compression and power question on a V6

[Tyson128]

I got a 95 Explorer Limited (ok I'm hooked). The person who owned it seized the engine. I plan to replace the crank, rods, mild cam and pistons along with some port matching.
I noticed in the teardown that the pistons are dished and I was wondering if I should replace them with a flat piston set to increase compression?
Will I have to move to and higher octane gas with stock head gaskets?

Your comments are invited

 

[jrowe6]

i have read about this and if i remember correctly yes you will. what i read is you can put the pistons from a sohc 4.0 v6 into a ohv engine and it will raise the comp. from 9ish to 10ish which will be a significant boost in power. you can do alot with tuning tho, im sure it could be made to run on 87 but with all the mods you are doing might as well tune it for 91 and get the most for your efforts.

http://moranav6racing.com/

they sell those pistons for pretty cheap sometimes.

 

[jd4242]

NO flat top piston with your 95tm heads will take you well over 11:1 not ideal for pump gas! If you want 10:1 you have to run first gen piston they are small dished with you 95tm heads!

 

[Tyson128]

I got in the short block yesterday afternoon. I finished the port match on the heads and lower manifold with a Ford blue repaint.
The new pistons which have a smaller dish are Definitely going in! The short block has a 8 bolt flexplate instead of the 6 bolt and is pretty clean. I ordered new rod bolts and bearings.
Comp Cams is getting a call for the 410 Boy AM I PUMPED!

 

[jd4242]

Post a pic of it over in the thread "before and after engine pics".also I would go 422!! If you can aford the dual springs the 422 works better with higher compression and will produce way more power.o and SI stainless steel one peice valves and melings high flow oil pump are a must!!

 

[Tyson128]

The Issue is: "Mileage"

Hey : Pictures are a rightous idea and are forthcoming. I have a commute 135 miles to Brooklyn from the Catskills on Mondays and Fridays back home. I need to design around creature comforts, reliability and $3.00 gas. Also, stop and go driving, occasional spanking of riceburners,camel drivers and beamers excepted
I'll lower the front end to accomidate air flow and beefy shocks and rear sway bar, add ceramic headers, and a flowmaster. Electric fan and shift kit
Those are the basics

 

[jd4242]

Well if you are planing on using first gen piston with your 95tm heads that will put you at 10:1 and 90+ gas will have to be used and with higher compression comes less reliability.

 

[Tyson128]

Mileage is the issue.

Keeping the oil at OEM temperture,(thanks for the oil pump idea) increasing coolant flow, and electric fan especially in stop and go traffic.
Octane at higher compression is ok, moving the operating range of the cam from 800 to 4800 usable (410) to 1200 to 5000 (422) is not.

 

[jd4242]

I have had both cams in my motor and can tell you that you can not tell the difference in when it starts to make power but the 422 makes way more power.you will be idling at almost 800 and the second you hit the gas before you even start moving your be at 1200.I idle at almost a 1000.99% of people that put it in wish they went 422. For that kind of money and how little power it increases its not worth it.