GR Yaris New mods, guess the BHP?

Duncan

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Earlier referred MPS with 380 or 'safe' 370hp on 102ron, they run 1,6 bar flat basically on stock valve springs. May very well be on or over the limit... Also nothing in the exhaust, 'cool' but very dirty and highly illegal in Germany....

Try the auto subtitle function if not understanding German:


If valvesprings, personally I like the pumaspeed turbo, not much bigger but with WRC core in combination with a metal catalyser would be nice balance of power, response and relative reliability.

PS: @Duncan when opening up the head, maybe put in better camshafts in while at it? Kelord have a set that is similar to stock but that hasn't got the pressed on lobes than can shift as they did on the Fensport sprint car...

Have seen the Kelford cams, was considering it, but for now I want to be able to revert to the stock ECU if needed. Fensport advised the Kelford cams wouldn’t work. Also at the power level the exhaust turbine/back pressure is the limiting factor.
If I go big turbo later down the line I’ll consider cams.
I’ve spoken to pumaspeed about their hybrid, waiting on more results from them first, and I’m in no rush. If I can get 350bhp is from the stock setup I’d probably put the cost of a turbo in to suspension first.
 
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MRA3

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In an ideal world I'd do something about the exhaust at the same time, but £ for £ I think the valve springs will do more than a HJS downpipes, hence going that route initially. Might test it without the GPF just to see the impact, but don't want to go all-out track car.
Out of curiosity, how much labor is involved on replacing the springs? It seems like it’s the first mode to do if you’re chasing more HP.
 

Duncan

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I’ll let you know once I get the bill!
Question of whether they can be done without taking the head off or not I gather.
 
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CommitConfirm

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Out of curiosity, how much labor is involved on replacing the springs? It seems like it’s the first mode to do if you’re chasing more HP.
I was quoted 7 hours by Fensport.

Question of whether they can be done without taking the head off or not I gather.
I've done other cars by pushing rope into the cylinder, more recently I've done it with compressed air.
 

Tralien

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Jan 29, 2022
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Just watched some vids from motivegarage and they tuned their yaris using motec. They switched the springs and were able to run 30 psi with stock turbo....must be like 2.0 bar. So going to 1.8 or 1.9 stable should give some serious power gains vs stock springs.
These guys just achieved around 350 hp :( with stock cat/opf but with intercooler upgrade.

Im so excited to see your results......changing springs should take 1,5 days they said btw...
 
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Duncan

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I’m waiting patiently now to find out how it goes. Though shouldn’t lose sight of the valve springs being as much about engine safety as extra boost. But yeah, more boost please at the top end.
I might even get the torque curve flattened as I like the linear torque to the redline, more like an N/A. The Yaris replaced a V12 for me (who thought you’d ever hear that?), I’d like to get it to match the performance ultimately, though that will require a somewhat larger turbo down the line once some others have found the limit.
 

Duncan

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After a bit of a delay I’ve got round one of the tuning results.

Hardware list is:
-Syvecs
-Airtec IC, boost pipes, turbo elbow
-ITG panel filter
-Kelford valve springs

So, deliberately left stock Cat/GPF/Exhaust for initial tuning.
Reason for this experiment was:
-to see how valve springs in isolation compare to others results with no springs but full turbo back exhausts (which cost much more than changing springs)

340bhp/420nm. At 1.7 bar.
Area under the curve from 2.3k to 6k is immense. Despite similar peak figures from ECU tuning one of the clear advantages to Syvecs is the torque spread (I’d hope so for the price!) note, still some squiffy differential stuff at 5.5k to ignore, and very top end wasn’t refined as this isn’t the final hardware state.
Also, the “before”here is with the mods, but stock ECU:

CC8B91ED-AD69-4A08-BBA0-0107D70C1276.jpeg


One observation is despite the valve springs there is still torque roll off around 6k. So it seems both the stock valve springs (as per others results) and the stock exhaust system are limitations at this level.

Next step is adding a HJS sports cat down pipe.
After this is I guess next limitation will be the stock turbo.

Closest comparison for similar setup but with exhaust but not springs is Pumaspeed’s 350 kit (Syvecs, IC, pipes, elbow, panel filter, Miltek sports cat/GPF delete/GPF back exhaust):

F06BE3A8-90D4-45A3-98A3-35530FC569E4.jpeg


So interpolating to 1.7bar it’s an exact match (340bhp/420nm), difference is just the curve shape.

So it seems different routes to same results, depending on if you want the louder exhaust note, or peace of mind if springs.
No right or wrong answer, but hope this comparison is of interest to the Zoo!
 

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Tralien

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wow....3 thumps up

to be clear: do you plan to keep your opf? As there is an ece cat from hjs available but no part for the opf, I am forced to keep the opf and Id love to see some results from people without opf delete.

very impressing results! thx for sharing your experience. I hope you do some small steps from now to see what parts deliver what results

did you see the kelford cams? they have several stages....did you think about adding the first stage which should run with stock ecu to reduce the boost needed? shouldnt be that much more effort if you change springs. and was it difficult or how long did you need to change the springs?
 
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Duncan

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Undecided on the GPF, may test it with a delete pipe but no run it in the road like that.

At the time I had the springs fitted no cams we in stock in the UK. Also I expect to go hybrid or G25 eventually, so would skip the EZ spec ones and go straight for the lumpier set.
No doubt they would improve volumetric efficiency, but I think the limit on the stock turbo is peak turbine flow rather than pressure ratio. Cams will make more sense on a larger turbo.
 

Duncan

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I’ve now got the car back, but not had a chance to use it too much yet.
Sedate 100 miles on motorways gave 45mpg, which was a nice bonus.
I can report however that the biggest unsung benefit of Syvecs is that hard breaking no longer triggers the hazzards!
That will improve A to B times more than the power increase, as I was only ever breaking to the sensor threshold for fear of looking like a tit to anyone nearby. Hated that feature more than the high seats or low mirror etc.

Back to the tuning, the HJS downpipe was fitted, OPF and rest of the exhaust remained stock. Pick up over OEM cat was 10bhp/10nm, so the OPF and standard turbo exhaust housing are a restriction, causing the torque dip post 6k.
Still, torque curve that flat from 2.5k to 6k, then flat power to 7k feels great to drive. Feels much happier to rev now.
This is running 1.7bar boost. Tapers to 1.5bar at the redline, as it makes no more power running it higher, compressor must be well out of its efficiency range.

Will get some GPS performance results when I have a chance.

Tuner was Ricky from RE Performance in Swindon. Would highly recommend.

801B39CD-8DCC-46C9-9DD3-08C22502CA1F.jpeg
 
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Tralien

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what do you think about springs now? when the opf / opfback is a huge restrictor, you cant use the benefit of 1,5+ boost at high rpms?
so can you say changeing springs only makes sense if you have opf delete?
turbo could run 1,5+ boost at 6000/7000 rpm if opf woulnd kill the torque? or do you think you need a bigger turbo to run more boost towards rev limit?

very impressive result. 350 hp with opf....great. looking forward to turn to the engine tuning....Im still at seats and suspension
 
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Duncan

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Can’t be conclusive without running with various permutations of hardware, but if you look at my earlier post with the Pumaspeed 1.8bar map (which is full turbo back exhaust without OPF) then my setup is very similar (at 340bhp with the stock OPF).
Therefore I’d say replacing the valve springs is an alternative route to max out the stock turbo vs doing the full exhaust. Cost is probably lower too. Adding the HJS probably made the cost compatible to a full turbo back, but allowed higher peak BHP.
I think the stock turbo is really the limiting factor there. Sure, I could do a OPF delete and exhaust and maybe pick up another 10/15bhp, but the cost of that would pay for a hybrid turbo and the gain would be 50bhp+, and changing the valve spring has facilitated that, which is a huge plus.
If I want planning to take it further in the future and wanted a louder exhaust then the turbo back exhaust would have got me to broadly the same place.
 
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Shaun888

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Hey all, I have a question that I am struggling to see an answer to.. At which power level should valve springs be changed? I am currently running a custom intake and downpipe (we have no emission or sound regulations) as well as a custom tune on the stock ECU. The boost is currently at about 1.7 - 1.8 bar. I want to ask my tuner if he can put it up to 2.0 bar. I am still going to do a customer intercooler prior to taking it for a retune.. Below is the dyno graph after the ecu, down pipe and cold air intake
 

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Duncan

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Most of the tuners talk about tapering the boost down after 5500 rpm ish on stock springs, so peak boost before is less important, but they stick to max 1.4bar at high RPMs.
Regardless of valvesprings the stock turbo won’t hold 2 bar all the way anyway.
 

Shaun888

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May 30, 2022
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I was mistaken with my boost levels… It’s at 1.5 bar boost throughout the range. I want to up the boost pressure to 1.8 and then tapper down at the end of the range… When I mentioned this to my tuner he said the ambiant level we are on is rather high and that the turbo might work too hard to keep that boost without damaging the turbo..
 

Michael Knight

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anyone has a dyno sheet before & after kelford cams update (stage1) - just curious where it adds.
Also how it affect used boost per achieved hp/Nm.

Have a distant dream that cams could be nice next level update at some point.
If it yields +30hp (?) with same boost I think its a good way to go.
Would it require syvecs or can stock ECU manage the changed cam situation without mapping?
 
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Michael Knight

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Don't have a dyno on only cams but this is when I first tuned with Syvecs on everything else stock accept exhaust. Milltek turboback with sportscat.
View attachment 8242

And then with cams and a slightly bigger turbo...
View attachment 8243

You can tell it nnow likes to rev! Don't know if stock turbo could hold boost all the way but the diffrence is huge!
Thanks for the charts - looks like Syvecs makes the biggest overall difference, then turbo and cams are more of incremental improvements.
Overall silly figures, your car must feel like a rocket!