DW 400 fuel pump. What a beast. Impressed.

[Cory S]

Factory pump died last week. 18V BAP probably took some life out of it. Wanted to try a DW 400 and see if it would feed 700+whp without a BAP. It sure did. Lambda/STFT’s looking great all the way up to 7800rpm.

I did remove the Anti-drainback check valve out of the top DW 400, because it closed up the outlet opening to a SMALLER than the factory pump outlet opening. I really think their “retrofitted” design would easily cause a solid 10-15% reduction in flow. I do get longer cranks without the check valve, but I know I’m getting maximum capability from the pump. I may add a high flow in-line check valve to try out in the near future.

I’ve attached a picture of the size of the yellow plastic ring that sits inside the outlet of the DW 400 outlet, and put it on top of the factory outlet to show how much of a bottleneck it creates.

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[Burkey]

Yep, she’s a good bit of kit.
I’ve had mine installed since they released it (no check valve) with no problems whatsoever other than the hot starts.

Anecdotally, both myself and another DW400 user (also no check valve) noticed a considerable reduction in cranking times on hot starts after fitting phenolic spacers under the blower. Makes sense that cooler fuel rails won’t boil the fuel as easily.

 

[engineermike]

I had one that came with the early Whipple kit with no check valve. I had the hot start issue as well. I still don’t fully understand it but vapor lock makes more sense than losing its prime. .

 

[Burkey]

I had one that came with the early Whipple kit with no check valve. I had the hot start issue as well. I still don’t fully understand it but vapor lock makes more sense than losing its prime. .

It definitely seems to have at least something to do with gasoline boiling at a much lower temp when it’s not under pressure.
Cold starts, fine.
Introduce heat into the rails, not fine.
Remove heat from the fuel rails via isolation from the primary heat source (the heads), much better. With only a sample size of two I’d hardly call it conclusive, but it at least makes sense from a physics standpoint.

 

[Cory S]

I am going to order this particular check valve. I will report back with the results of any fueling changes, and starting issue.

https://www.highflowfuel.com/i-2390...MIy8OQ0YOo6QIVI_3jBx0P4A28EAQYASABEgIoY_D_BwE

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