Turbo Xflow ... worth it?

[Dyno]

Suck through Weber is a lot more difficult than SU. SU's don't have progression holes. So you can remove the throttle plate and put it 1 meter before the carburetor and it should still be working (if you don't get freezing). Not the case with the Weber. The plate must stay there. A second plate is needed to keep the turbo out of suction. The link of both throttle plates will become critical. You will have to measure the depression difference all the time until you got it spot on. Trying hard not to see deep vacuum between the carburetor and the turbo inlet. A real mechanical seal on the turbo can be easier.

And using one DCOE in front of the turbo will not make tuning easier. The turbo will see both bores at the same time. OK for full power but light load tuning will take a lot of time. A progressive carburetor as the DGAV can be easier. I would prefer SU HIF for a road engine. Specially because the fuel mix is so well.

[Dyno]

EFI can have better fuel distribution (in theory). Less prone to freezing because injectors are close to the inlet port. But because they are close they don't cool the mixture as with a carburetor manifold (when injectors are not placed close to the inlet but at the carburetor place.

[SidewaysMk1]

cc'ed up my 1700 and it has 9.5:1 Cr. Will this be too high for a boosted engine with standard cast pistons at 7 psi? 276 duration cam and crappy pump fuel??

[Miniliteman]

I would say yes.

[SidewaysMk1]

thanks..was thinking so, but want the opinion of ppl who know better.

[noisymime]

cc'ed up my 1700 and it has 9.5:1 Cr. Will this be too high for a boosted engine with standard cast pistons at 7 psi? 276 duration cam and crappy pump fuel??

I think your compression will be OK, assuming you can keep the fuel up to it. What carbs are you using?

That cam though is going to be a problem. You need something with less duration than that or you're going to run into issues.

[Graham]

cc'ed up my 1700 and it has 9.5:1 Cr. Will this be too high for a boosted engine with standard cast pistons at 7 psi? 276 duration cam and crappy pump fuel??

if it wasnt for crappy fuel id say the cr is right on the limit at that boost. re cam find a std one! while your changing it stick the pistons in a lathe and make the bowls a bit bigger

[SidewaysMk1]

maybe able to find a 1300 cam and some 1600 crowns, the ones with no valve cut outs. fuel is usually around 91-94

thanks...for advice.

[SidewaysMk1]

would 1.8 diesel pistons be a good cheap option for boosted xflow? they arent much heavier than standard pistons, but was figuring they would be very strong.

[Graham]

diesel pistons are a lot heavier, gudgen pins are massive too

[SidewaysMk1]

they was a 10g diff compared to the xflow ones i had...not using the diesel pin, was looking to get an offset bushing made dropping it down the bore n using standard xflow pin.

[Graham]

never heard of anyone fitting a bush to a piston

[Jack1995]

So i just found this thread and I'm looking to turbo my xflow. Ive made my decision to do it after reading everyone's opinions. Basically what I want to know is what I need? I've got a standard xdlow bored out to 1660. Shall I do anything to the internals? Cams? Valves? Rockers? Forge pistons? Balance bottom end? So basically what do and don't I need please? Thanks all

[looneytune]

Depends on what you want to use car for, target power and most of all, your buget. In most cases the standard cam is sufficient along with standard valves. A gas flowed head would be ideal. Forged pistons if going for high boost and if budget allows. A full engine balance and a lightened flywheel

[bytesandbolts]

My Turbo Xflow (Bog standard 1.3) I have been running for over 2 years with EFI with no issues. That was until 3 weeks ago when I blew a suspected piston. Will be rebuilding with forged pistons for sure!

[Jack1995]

Only looking to run low boost as a fast road car, how much will an engine balance and forge pistons cost me?

[Jack1995]

And I'm running carbs not injection? What's thoughts? Not interested in injection really I want to keep carbs. What's best turbo?

[bytesandbolts]

Can't say about the engine balance, but forged pistons for a crossflow are about ~£125 each.

[Jack1995]

What turbo is best?

[bytesandbolts]

Too vague of a question to answer mate.. depends how deep your pockets go I guess. Whatever turbo you use, you gotta find a suitable turbo manifold also.

[Jack1995]

Well not loads like but ideally? Like what's good what's not? Ideal world like?

[bytesandbolts]

I went for cheap and cheerful. So picked up a Garrett T15 from the local scrapyard for ~£70. Spools up by 1100rpm 8psi from my 1.3.

[Jack1995]

Thanks mate!!! Great help

[Graham]

Only looking to run low boost as a fast road car, how much will an engine balance and forge pistons cost me?

forget balencing, you dont need it.

forged pistons around £600 a set

[Jack1995]

Right so I picked up an engine yesterday, stripped it down today (guy didn't know what it was). It is a 1660 xflow 711m block. Lightened pistons, double valve springs and big valves. It has a fast road cam aswell. Now first thing the valves are not flush with the head? I'm sure they should be?. And what would everyone have done extra to the engine internals ? Ported and polished? Thanks

[Graham]

x/flow valve should NOT be flush with the head, if they are they are badly recessed.

if your turboing it, forget polishing or further porting the head, but change the cam for something milder, use a stock gt profile or perhaps high torque cam

[Jack1995]

Okay great . why not port? And how do people get 150bhp without doing hardly anything to internals?

[Dyno]

150 Bhp. The turbo will do this for you.

Keep CR low (8-8,5/1), I guess in you engine it currently will be higher. Use standard camshaft, max GT cam but I would even advise less. Reuse the double valve springs. Porting will not make it worse (unless not enough material left and making things week) but a good clean up is al what is needed. Must say, compared to Pinto's, KENT engines do have small ports, some grinding may help on a serious engine. Better spend money on a good (multi shim) head gasket, decent oil pump, oil cooler, etc....

[Jack1995]

That's great thanks a lot!!!!

[noisymime]

but a good clean up is al what is needed. Must say, compared to Pinto's, KENT engines do have small ports, some grinding may help on a serious engine.

I saw good benefit on my mild xflow when the inlet ports were opened right up. I'm only on 7psi, but even at that low boost, opening the inlets up really lets you get the benefit out of the turbo (Particularly if it's a low volume turbo). Unlike a NA engine (And depending on the size of your turbo) you can open the ports right up without experiencing problems with low intake velocity as you can rely on the boost giving you that.

Be careful with the exhausts though. Opening them up too much can impact your exhaust speed and affect boost times.

(All of that is purely anecdotal. Your mileage may vary)

[Dyno]

Yes, I can believe this. I've only done little work on KENT engines. I do know, even for an almost standard road engine, preparing the head did more to power as it did for a Pinto (who already got big ports). I remember the port start big enough but reduce very quickly. On a turbo, I should think the effect is less as in NA engines so if I have to cut my budget, I go for other parts first (unless you can do the grinding yourself).

[Jack1995]

Right so I picked up an engine yesterday, stripped it down today (guy didn't know what it was). It is a 1660 xflow 711m block. Lightened pistons, double valve springs and big valves. It has a fast road cam aswell. Now first thing the valves are not flush with the head? I'm sure they should be?. And what would everyone have done extra to the engine internals ? Ported and polished? Thanks

So is the best thing to do put a standard cam back in and forget porting?. Is there anything else I can do to gain power?

[caprimentle]

Is there anything else I can do to gain power?

thing is, making power is the easy bit, nothing like the hard work an na engine needs, more boost equals more power (without getting technical). it's making the engine strong enough to take the power. a correctly sized turbo, something like a t20 or t25 at 1 bar of boost is basically doubling the efficiency of the engine, so a 70bhp crossflow should now be about 140bhp, easy to get the power. but making sure you don't melt or break pistons on the cheap is the harder part.

[Jack1995]

That's great thanks a lot (y)

[looneytune]

Tbh i've always found xflow pistons not to be as strong as pinto ones therefore i would limit boost to 7 psi. Are you stil going carb? If so a reno 5 turbo carb will fit the xflow single choke manifold. All you have to do is drill the holes bigger on the carb

[Jack1995]

How do I know if my conrods are steel?

[Graham]

post a picture

[Jack1995]

will do later. also to decompress it should i be looking at using 1300 rods? or just a decompression plate? if so where can i get one?

[Graham]

1300 rods will be too short, 1500 rods from a pre x/flow or lotus might be the way to go

ferriday engineering will make you a decomplate http://www.ferriday.co.uk/decompression-plates/

however i would prefer to use either shorter rods or machine pistons to drop the CR

[HonkyWhiteTrash]

Fit an early crossflow chambered head to lower the compresion with late type 1600 crossflow pistons. Should give approx 8.0:1 comp ratio.