9mm to 7mm conversion

[Ace]

As an alternative you could just take a drill and put 9mm in holes in your 7mm cylinder head. It would be faster and cheaper!

I think it would probably take me days to get the head r&r'd + alot more $ and additional waiting time for a new one to arrive after I finished butchering the stocker.

In any event, I'll be waiting to hear more about the results of this experiment....

[KTA]

It wouldn't really be an experiment since there are lots of 7mm heads bored out to take the 9mm tips.

[Ace]

I was talking about the experiment with turning the 9mm tips down to 7mm....

[KTA]

Oh, well that has been done too, should work great, be just like stock.

[Ace]

I thought the 9mm injectors were slightly larger flow-wise than the 7mm's.

[Richie O]

Oh, well that has been done too, should work great, be just like stock.

[Richie O]

I thought the 9mm injectors were slightly larger flow-wise than the 7mm's.

They are a nice injector for 300 to 350 horse. I run 300 at the wheels in my 89 with a stock tranny. They go nice. Stock cooled sticks are turds. I drove my 93 for about a month before they came out.

[Smokem1]

If I recall correctly, the customer lost ~ 90hp dropping back to the I/C injector vs this set.

It wouldn't really be an experiment since there are lots of 7mm heads bored out to take the 9mm tips.

And a different sleeve nut.

[Richie O]

The same day my 89 ran 297 on the dyno a 93 with a rag ran 275 with a ground pin and the pump at max with his 6x.009's. Im not sure how much my slushbox eats for power but I bet its a good 50 horses. It would not surprise me if it was a 90 horse difference between the 2.

[Smokem1]

They are done and ship to him tomorrow, we'll see.

[KTA]

I thought the 9mm injectors were slightly larger flow-wise than the 7mm's.

They are I meant they would be just like stock Non-IC tips since that is what they are. Of course this particular set has pintle mods, which may or may not make much diffrence depending on the fueling the pump is set at. I thought when I 1st read this that this was a NON-IC motor that already had these injectors but was swapping the later style head onto it and wanted to keep the injectors the same. Since if that is the case there is a head swap going on with the injectors at the same time it would be hard to verify if they ran any diffrent since you couldn't tell if any difference came from the head or the injectors.

[Smokem1]

Was 9mm head DSLA155 P104, now 7mm head DSLA145 P265, will be 7mm head DSLA155 P104. Going back to the 145° pattern without adding ~ 10° static advance wasn't helping either with the 286210 piston.

[KTA]

So actualy this will be a comparison between IC injectors and modified Non-Ic injectors. Should be a big diffrence since the Non-IC flow so much more. BTW what is a 286210 piston? This engine a custom build?

[Ace]

It wouldn't really be an experiment since there are lots of 7mm heads bored out to take the 9mm tips.

I'm curious to what the rationale for this would be. I guess maybe they could run a P-pumped engine and custom 9mm injectors with huge holes and maybe mitigate the issue bgilbert asks about:

Very neat. How much does this weaken the dinosaur tip ?

But that would seem an overall disingenuous idea, especially in a big power engine, unless of course they were throwaway heads the owner just wanted a couple pulls out of and didn't care about. I though the whole reason for the 7mm head was greater reliability through resistance to cracking out the injector bores.

[KTA]

Scheid diesel does it fairly often and I know Haisley has as well. They do it to run a total different injector body. It allows for more flow and then they can use commonly available tractor pull tips. Head cracking is not an issue in a all out race application. FWIW though my 89 head cracked the exhaust flanges off from a shrinking manifold before the head cracked in the injector bores. I know both heads can crack from heat as I have seen plenty of 7mm heads with cracks in the injector bore. I think the 9mm heads are probably more prone to this problem, but I don't really think it is a big issue. It is very rare to find a head cracked so bad through the bore that it leaks, and if it doesn't leak the cracks don't hurt anything.