Xu9 mi16 head on xu10 block? Or maybe an ew10?

[SPofRCLD 0 1 Cars]

Hi!

Have searched the forum for a couple of days now but dont seem to find all the info..

I have probably killed my 1.9 mi16 motor on the last track day i attended, i believe due to oil surge, but will only know tomorrow. Anyways, im trying to figure out if:

a. Will a 1.9 mi16 head fit an xu10 rfv block without any major mods? And what about an ew10 rfj block?

b. What are the pros and cons of such a combo?

 

Reason im asking is because im running itbs on custom adapters +management, and original 1.9mi exhaust mani that id like to keep, and with the price of a rebuild it seems way more cost efficient to just swap to a more modern block.

thanks in advane.

[petert 586]

The XU9J4 head will bolt straight onto any XU10 block. Use nine XU10 head bolts. The 10th, over the water pump, needs to be an XU9D bolt, with the head turned down a bit, so it fits in the hole.

[SPofRCLD 0 1 Cars]

Thanks peter! Are there any benefits to going down this route, The xu9 mi dfw head on an xu9j4r block?

[petert 586]

You mean XU10J4R block? The XU9J4 and XU10J4R heads are basically identical in terms of valve size and port size. The benefit in my mind, is the cheap and easy cam swaps with the XU9J4 head. The cams in the XU10J4R head are very small. Thus unless you swap them for XU10J4RS cams and valve springs, or buy new billets, your choices are limited.

[SPofRCLD 0 1 Cars]

Yeah, thanks, i did mean the xu10j4r block. Will i be increasing my chances  for oil surge with the mi head? And are standard dfw cam-head combo has better flow than standard rfv?

[petert 586]

12 hours ago, SPofRCLD said:

Will i be increasing my chances  for oil surge with the mi head? And are standard dfw cam-head combo has better flow than standard rfv?

Yes, but the bottom end is better. If you add 0.5L extra it won't be a problem, unless you're on sticky tyres.

 

The heads flow the same but the D6C/DFW cams are bigger than RFV.

 

[SPofRCLD 0 1 Cars]

Im on toyo r888r’s, i believe they are considered pretty sticky.. i might have sourced some RFS cams to fit in the rfv engine, so might drop the mi-head-rfv-block idea, bit cant seem to find an answer in any post to will the cams fit with the standard rfv springs and not the double the rfs head has..  

[petert 586]

I think you'll find it will be dangerously close to spring bind.

[SPofRCLD 0 1 Cars]

What are the solutions to that? Will changing to the rfs double springs do the trick?

[petert 586]

And retainers, spring bases, seals etc.

Edited May 27, 2018 by petert

[SPofRCLD 0 1 Cars]

Okay, thanks peter! Now i just need to find a set of springs then, as i already have the cams, but the springs are pretty rare here