So I'm debating weather to buy a 6l block or use liners to get to my goal of 7.0 liters. If I ofset grind thecrank to use 1.888 honda journal rods I can get a stroke of 80mm and then using 96mm liners get 7.0l the only draw back is I wwon't be able to get the larger oil pump from the 6l block. Is it really worth it?

 

cal your kinda swimming in uncharted waters, only way to find out is do it!

the plus is<when your done> your will have had good learning experience!

gotta say, if its your 1st major engine build, wow.

like i said earlier ,GO FOR IT. engines are a lot of fun!

 

I was talking to a guy here in Aus who has done a few offset grinds on 5.3 cranks and you need to allow at least 20" for roundness grinding.

Also when you do this have the journals radiused this will increase their strength. Do a google search on the NASCAR cranks, these guys run the Honda journals and see how they are prepared.

 

the guy i went to about grinding the crank, builds circle track motors and he gave me the idea. im just curious on if i can find pistons with the right pin height.

 

Chev pistons are pretty cheap - buy the blanks and have them machined to fit.

Remember 700hp V12 is just under 60hp per pot equivalent to a 500hp V8, so I don’t think you need to go the expense of forged units, I would look at HPC coated high quality cast alloy. These stand up to 300hp+ in a Subaru 4 cylinder.

 

Know of any good places that sell them? The problem is 90mm is smallee than any gm piston and its an extra 450 $ to get the block bored and honed

 

I do not think the oil pump will matter. there is a huge overcapacity in the pump, loads of pressure bled off by the oil pressure relief valve, unless you are doing the Le Mans 24h (ie hour after hour flat out) you will be fine - even then, probably fine! Keep the oil cooler though.

Greg

 

DO I understand you are not going 96mm bore?

If so bore the liners to accept 93mm pistons then there are Ford GM and Subaru units available.

Regarding oiling the stock pump is up to the task. the biggest issue is oil surge in the sump. If I were you I would add a baffle to the sump, Have a look at this idea.

XJ-SC Modifications

 

ques; why would Ford engineer a larger pump 6L, if present one 5.3 was plenty?

and after you build a great motor, what could happen if oil pump was NOT sufficent.

just asking? spend money now or spend,alot, later.

and nothing wrong with a piston that is cut from a blank, but few machine shops like to cut a cheap piston, especially when they know a forging is better aluminum to work with,and overall a better way to go.

back to the money, if you cut corners in a hi-performance engine,it may come back to bite you.

and you say you are going to bore the block,? you dont bore the block in slip-fit liner
blocks, you bore the liners using a fixture to hold them,then bore the liners with a bore-bar. + hone fit each piston to the jug.
unless you are gonna use big bore kit liners 96mm + anyway. if so, be ready for much
more detail work in the final assembly.

Darn that sounds like FUN.

 

I am not 100% sure if I'm going with liners or not yet. Depends what budget will allow. Thinkin of doing the 6l stroke and 96mm liners. That would give me 6.8 liters

 

the more liters you make wont help much if they cant get enough air, they gotta breathe!

a quick thought; what if,instead of trying to suck the air into the cylinder, you forced the air in.

bet you could make less liters,do more power,than cubic displacement.

 

I'd get new light weight pistons and custom rods and offset grind the crank leave the bore alone to make the engine more square. A more square engine will give you a flatter torque curve. Over square engines tend to be peaky and difficult to tune. Then focus your dollars on induction, fueling and ignition.

There aren't many options for intakes...so I'd consider sending your Intake manifolds to be extrude honed. That process did wonders to wake up the BMW v12.

For the fuel and ignition you can use two systems, one for each bank. If I were you I'd use the fuel and ignition system from a 1990 to 1995 Nissan 300ZX. This system is sequential injection and direct coil on plug ignition so you can rev that V12 to 6500 cleanly. The entire fuel and ignition its driven with CAS or crank angle sensor that is driven off the camshaft and could easily be adapted into the jag distributor. It's optically triggered so you can put and 2nd optical sensor on the trigger wheel offset 60 degrees to drive the 2nd bank or just stack two because they are very flat. The system is very simple, has few sensors uses a modern hot knife style MAF to measure air flow and there is software available to tune it's easily called Ztune. Nissan got 220HP out of 3.0L so for your 440HP would be the starting point. A well tuned 6.0L will make more power than a sloppily tuned 7.0L engine.
This way will get you more RPM and cost less than an aftermarket system. The largest problem will be adapting the CAS to the jag dist but I think it can be easily done.

In the 90's I Bored and stroked a Porsche 4.7L v8 to 6.2L at great expense. The engine fell flat on it's face at about 5000Rpm becasue the induction couldn't feed the engine. I loved the torque but it wasn't very usable.

 

how much would i be able to squeez out of a 6l flathead? i want to be able to make 500+ as an end result.

 

If all the racers in the UK know anything, which they must do, a flathead has to be the easiest way to get better breathing, as long as you are Ok about fuel useage! Having said that, there is a very knowledgeable and capable guy in Australia Norman Lutz, who has got huge power out of the HE.

Greg

 

Well have a set of flathead heads that I just bought a couple weeks back from icsamerica. I have to come up with the final plan, most likely im going to end up boring 10 or 40 over allowing me to use 4.6 pistons and gm I beams. Most likely offset grinding a 5.3 or a 6l crank. Giving me 6.4ish ltrs and then using flatheads and aftermarket engineanagement

 

HI, icsamerica,finally some one else Extrude honed some inlet manifolds,

i Extruded my jag manifolds,plenums and runners, after opening up the TBs 6mm each, ported the ports and used 3mm oversized inlet valves, exhaust valves i sized down to 2.5mm ,just to make them fit properly.

also something i believe helps my engine for durability, i had the complete flat head surface thermal barrier coated, along with piston tops, both valves and(most important) the exhaust ports, my reasoning was to keep heat out of the head cooling jacket, cooler area around the dreaded valve seat drop, problems.

just some thought for others reading these posts, i have many small engine mods,cant remember them all, been 16yrs.