Turbo spool question?

[dac69er]

My turbo setup on my forged build boosts up really strangely. I'm not sure if this is to be expected or I am missing something?

If I floor it at lower rpms, I get pretty much 0 boost until about 4k rpm and then it goes from 0-full boost within about 150rpm. It's like a switch. This makes the car really shitty to drive as it is very all or nothing.

My other 2 starlets (ct9 and td04) all build boost at lower rpms. The boost curve is more gradual up to full boost. As I have at least some boost lower down, those cars are more fun to drive and arguably quicker round back roads.

Why does the turbo on my forged setup react like this? It's only a hybrid td04, so isn't anything wild.

 

[Jay]

Would agree with you on the response front, nicer to drive when you have some power lower down.

A forged engine is usually built with lower compression so there's a payoff regards drivability versus high end power. That's not to say you can't have a bit of both.

What sort of boost control are you using?

 

[dac69er]

Would agree with you on the response front, nicer to drive when you have some power lower down.

A forged engine is usually built with lower compression so there's a payoff regards drivability versus high end power. That's not to say you can't have a bit of both.

What sort of boost control are you using?

My forged build has pretty much stock CR. I specifically did it that way to cut down on any lag or poor response.

I'm just a bit disappointed with the whole thing as it's not as powerful as I had hoped and the response isn't great either. It's actually ok off boost tbh, but it's the way the boost comes in that is a bit off.

I have a tial external waste gate and a Greddy profec b spec 2. I'm using a 0.8 bar spring and running 1.2 low and 1.4 high. It's laggier than expected, although I was told it would be a touch laggier than a stock td04 which is fair enough and once it's on boost it holds perfectly all the way to the redline. It's just below full boost it is pretty flat as it builds minimal boost under about 4k rpm

Maybe I am expecting too much, but it doesnt seem right to me!?

 

[Jay]

At least that should rule the CR out.

Sometimes you can tinker with the boost controller to increase response, near sure the Profec B has that ability. How much you can improve it will depend on the car/engine/turbo though. If you have had it on the dyno it's probably close to optimal anyway but worth mentioning.

Can't comment on your expectations but these are the scenarios that lead people to 5E builds, boost by gear set ups, smaller intercoolers and shorter piping just to get that turbo spooling a little quicker

 

[SKINY]

The controller I have here has gain and boost, gain is how hard the turbo comes in, nearly sure even the Profec A in the Caldina has it, it has 2 step setup, it reads boost and gain

 

[dac69er]

Yeah, I have the gain and set gain. Set gain is the point at which the controller starts to control. Before that the waste gate is fully shut (or should be at least). I have this set to 0.95bat I believe.
I can't set it much higher than that otherwise I get over boosting.

I will take a video of it boosting next time I use the car to demonstrate what I mean.

Any ideas of anything else I could look at as I am pretty sure the boost control is setup correctly.

 

[gorganl2000]

i've not experienced that with my various set ups..but as Jay mentioned, i went 5E very early on to try to minimise the risk of such things.

however, my close friend experienced very similar to you in his ep82 ...he had a stock td04l on his setup which responded well and built boost gradually...he then decided to upgrade the compressor wheel and compressor housing to something larger (highflow/hybrid) keeping the stock td04l back end...the end result was a turbo he hated, no boost at lower/mid rpms, then full boost very quickly for the mid/top end....so it could possibly be a characteristic of your hybrid turbo on the set up

your EBC seems to be doing its job,,,,so you can look at your tune to see if anything can be done to help the situation

also try a datalog,,,it may be useful in your assessment

 

[dac69er]

I agree, it feels to me like it's turbo related. Wouldn't be so bad if I got better than stock td04 power with the lag characteristics. But I have pretty normal stock td04 power but with the lag characteristics. The worst of both worlds!

I'm tempted to junk to turbo and just get a stock one. It was just quite expensive

 

[gorganl2000]

you could try a stock tdo4l...you can buy a cheap used td04l or if you're lucky, borrow one from a good friend/member who may have one laying around...install it and get a tweak to your tune to suit....it's a fairly straight forward swap, ,,you would then be able to make the comparison and answer all of your questions

yeah, it would take a bit of physical effort and a little more budget...but peace of mind is a good thing

if you tried the swap and prefer the stock td04l on the set up...you could always try to sell the hybrid unit to recover some of your funds

 

[Calum122]

My brothers Starlet, runs a hybrid TD04 on stock internals, is probably similar. For daily use this makes it quite ideal, since it's off boost 90% of the time, but the car has never been a daily and I think he appreciated driving my stock CT9 as it was just more responsive.

I wanted to go somewhere in the middle, like TF035H turbo. TD04 pressures but with an earlier spool. I did have a few, but engine went and haven't touch the car since. I think a hybridised CT9 making 200hp would be the sweet spot for me, giving how hard it is to find bits for these cars these days.

 

[dac69er]

My brothers Starlet, runs a hybrid TD04 on stock internals, is probably similar. For daily use this makes it quite ideal, since it's off boost 90% of the time, but the car has never been a daily and I think he appreciated driving my stock CT9 as it was just more responsive.

I wanted to go somewhere in the middle, like TF035H turbo. TD04 pressures but with an earlier spool. I did have a few, but engine went and haven't touch the car since. I think a hybridised CT9 making 200hp would be the sweet spot for me, giving how hard it is to find bits for these cars these days.

I will be honest, I kinda preferred the car with the hybrid ct9.

I have thought about going back to that.

Although my ep85 with a stock td04 is quite nice, the power is more gradual so it is more fun on the road than they hybrid td04

 

[Djaniero]

Sorry to hear you're still having niggles with this build Duncan. As said above, I'm sure you'd sell the hybrid unit on the bookface pages no problem to try and re-coup some of the cash and try a stock TD04 instead. I too often miss the quick spool of the ct9, but I'm hooping for a similar feel once I go 5E with the vf28 I have gathering dust in my garage.

 

[daniel_g]

Suppose it will depend on the dimension and blade design of the compressor wheel. The journal bearing doesn't help.

On the whole I didn't think the 'hybrids' were that impressive either. Mine made the same power or less than a stock TD04 at 1 bar. I'd do a comparison on the spool time but its sold.

I know you've just put it all back together, but a lightened flywheel would help the engine rev up quicker.

Is your exhaust heatwrapped? Could be a myth but isn't that supposed to reduce spool time. Turbo blankets too.

Other than that you are into the likes of a ported head, custom cams and a rear entry intetrcooler setup.

 

[dac69er]

Suppose it will depend on the dimension and blade design of the compressor wheel. The journal bearing doesn't help.

On the whole I didn't think the 'hybrids' were that impressive either. Mine made the same power or less than a stock TD04 at 1 bar. I'd do a comparison on the spool time but its sold.

I know you've just put it all back together, but a lightened flywheel would help the engine rev up quicker.

Is your exhaust heatwrapped? Could be a myth but isn't that supposed to reduce spool time. Turbo blankets too.

Other than that you are into the likes of a ported head, custom cams and a rear entry intetrcooler setup.

It was a full kit from wepr so I hoped they would sell something that was tried and tested and would work well!

Part of the exhaust is heatwrapped. Mostly due to it running close to certains things as the fitment is so so.

I have an orc clutch with lightened flywheel, so sorted there. Tbh, I don't find it much different to stock.

I got the head lightly ported when I got it rebuilt and skimmed.

 

[gorganl2000]

I will be honest, I kinda preferred the car with the hybrid ct9.

I have thought about going back to that.

Although my ep85 with a stock td04 is quite nice, the power is more gradual so it is more fun on the road than they hybrid td04

i have similar thoughts...option (1) 4efte with a hybrid ct9 and option (2) 5efte with a stock td04l,,,those were my favourite set ups for daily driving

 

[SKINY]

This is why I've a tf035 kit sitting, I've been in a few td04 cars and it was a waiting game until 4k rpm then all over in no time, grab another gear and wait lol
Also kept pace with a td04 car before on a good run out to mondello, in fact I had to back of a few times in case I bumped them, the face I saw in the mirror said it all lmfao
That member shall remain nameless lol
When I was asking about turbos the tf035 was touted to me as still boosting low down rpm and a decent increase in power over the ct9
Time will tell I suppose, it will be fitted along with my fpr and fcd and fuel/air guage then get the big legend to get the fancy ear muffs out up the Kirky straight

 

[dac69er]

Stock td04 isn't bad at all imo. I have one of those on my other car and I like it.

I did like the hybrid ct9, but just felt I needed a little more oomph

 

[gorganl2000]

i've not experienced the tfo35,,but based on the reports,,,it does seem like the perfect fit between a ct9 and td04l on a 4efte.
i've always wondered how it compares to a hybrid ct9,,,seems close enough, but maybe with slightly better top end???